Blockchain in supply chain management: a multiple case study analysis on setups, contingent factors, and evolutionary patterns

Abstract Despite the hype about blockchains among supply chain management (SCM) practitioners and researchers, the technology’s adoption is still low, and confusion remains about its potential benefits for operational efficiency and effectiveness. Building on a multiple case study research, this paper clarifies current value creation opportunities enabled by the blockchain for product/material tracking and tracing. We highlight that the setup of blockchain projects depends on the presence of different drivers on customer value or efficiency and the focus towards products/components or raw materials. Based on how tracking and tracing drivers and focus influence the initial blockchain setup, contingent factors are discussed and possible evolutionary patterns are identified. These findings are elaborated in one setup matrix and three propositions. The study is one of the few to add empirical evidence to the mainly conceptual SCM blockchain literature and provides a middle-range theoretical contribution based on contingency theory. Furthermore, it offers actionable guidance for managers and policy makers about SCM blockchain adoption.


Introduction
The blockchain has been hailed as one of the most promising among recent technological innovations in the field of supply chain management (SCM).Blockchain featuressuch as the distributed and immutable peer-to-peer data infrastructure (Cole, Stevenson, and Aitken 2019) have led many companies to launch pilot projects with diverse purposes (see Kshetri 2018;Fosso Wamba and Queiroz 2022;Van Hoek 2020).Examples span different industries, including automotive (BMW Group 2020; Volkswagen AG 2019;Volvo Car Corporation 2019), textile/clothing (Arthur 2017;Ledger Insights 2019) and agriculture/food (Louis Dreyfus Company 2018;Nestl e 2019).
Despite the growing interest, the actual uptake of the blockchain has been characterized by few rollouts beyond the pilot phase, lower-than-expected adoption rates, and a recent loss of investors' enthusiasm (Kouhizadeh, Zhu, and Sarkis 2020;2021;Schlecht, Schneider, and Buchwald 2021).Lately, several calls have been made for academia and practice to address the factors holding the technology behind its ascribed potential (Fosso Wamba and Queiroz 2022;Durach et al. 2021;Nath et al. 2022).In this sense, recent studies have explicated possible applications (Kopyto et al. 2020), analyzed drivers and barriers to adoption (Chang, Iakovou, and Shi 2020;Vu, Ghadge, and Bourlakis 2021), conceived decision models identifying the most suited technological configuration (Bai and Sarkis 2020;Farshidi et al. 2020), and leveraged established theoretical lenses to derive implications for implementing companies and their supply chains (SCs) (Schmidt and Wagner 2019;Gligor et al. 2022).
Although these considerations of general applicability are the precondition for managers to approach blockchains, the next step should be to investigate their suitability and actual application in specific contexts in order to identify emerging patterns.Some empirical studies (Hastig and Sodhi 2020;Rogerson and Parry 2020;Gligor et al. 2022) suggested that firm and environment characteristics may determine the setup (i.e.technology selection, information to be included, partners to be involved, rules of engagement) and implementation patterns of blockchain initiatives.These environment characteristics have however not been adequately investigated as contingencies generally applicable for determining blockchain setups in SCM.This is also due to the specific industry-focus of most empirical studies so far.Furthermore, it is not clear whether these contingencies play a different role during the different phases of a blockchain implementation process, which hinders the understanding of adequate starting points for it.
This paper thus aims to support the identification of the most relevant contextual dimensions affecting blockchain implementation for SCM purposes by answering the following research questions (RQs): 1. What are specific blockchain SCM setups? 2. What are the contingent factors affecting the choice of a particular setup?
Our approach is in line with middle-range theorizing on blockchains in SCM (Treiblmaier 2018).This is particularly relevant as empirical studies on real cases are still scarce (Durach et al. 2021;Rogerson and Parry 2020;Srivastava and Dashora 2022).Drawing from a multiple case study analysis on SC partners and service providers involved in blockchain projects in SCM, we develop three propositions elaborating the core tenets of classical contingency theory (Donaldson 1987(Donaldson , 2001;;Lawrence and Lorsh 1967).Overall, our study revisits some messages emerging from previous literature on blockchains in SCM.Thereby, we shed light on how traceability/trackability drivers and focus towards products/components or raw materials enable a systematization of blockchain setups.Moreover, we discuss how the characteristics of the general environment, the product, and the SC influence the choice of the setups that are suitable for blockchain applications in SCM (e.g.Chang, Iakovou, and Shi 2020;Nandi et al. 2020).Finally, we elaborate potential evolutions of the identified setups for blockchains in SCM.
The remainder of the paper is organized as follows.The next section provides some background on the blockchain technology and the debate within the SCM community.Then we illustrate the methodology, followed by presenting the expert interviews' findings and the case studies.The discussion analyzes commonalities and differences from the practical experiences to elaborate propositions for future research and practice.We conclude with the implications for researchers and managers.

Blockchain technology for supply chain management
Blockchains are a particular type of Distributed Ledger Technology storing transactional data and related information, secured by cryptography and updated through peer consensus (Cole, Stevenson, and Aitken 2019;Schmidt and Wagner 2019).Blockchains consist of nodes, each containing a copy of the distributed database, called Ledger, where all transactions are recorded (Wang, Han, et al. 2019).The transactions occurring over a given period are registered into a 'block', which is connected to previous blocks through the hash function creating a chronological chain of blocks and guaranteeing the immutability of data (Wang, Han, et al. 2019).
Originally developed in the field of cryptocurrencies (Nakamoto 2008), the blockchain is now regarded as a foundational technology that can evolve to the needs of different contexts (Falcone, Steelman, and Aloysius 2021;Ozcan and Unalan 2022;Wustmans, Haubold, and Bruens 2022).As it provides flexibility to handle different sets of data, the technology has been gaining traction in various sectors including finance, healthcare, tourism, government, media, and entertainment (e.g.Cole, Stevenson, and Aitken 2019;Fosso Wamba, Kala Kamdjoug, et al. 2020;Scott, Loonam, and Kumar 2017).The transactional nature of SCs coupled with ongoing technological and organizational barriers to information sharing made SCM a natural candidate for blockchain application (Azzi, Chamoun, and Sokhn 2019;Kshetri 2018).
The literature distinguishes three types of blockchain technology: public, private and consortium blockchains (see e.g.Cole, Stevenson, and Aitken 2019;Schmidt and Wagner 2019).In public blockchains, anyone can freely join the network, all transactions are publicly visible, and consensus is achieved through the work of miners solving complex algorithms, such as Proof of Work or Proof of Stake.The cryptocurrencies of Bitcoin and Ethereum are typical examples of this variant.Private blockchains are instead centralized networks controlled and regulated by a single organization, which validates transactions and invites authorized participants to join the network.Finally, consortium blockchains are partially decentralized solutions, controlled by a group of pre-selected nodes deciding which participants can join the network.
Related to SCM, previous studies (Saberi, Kouhizadeh, and Sarkis 2019;Kouhizadeh, Zhu, and Sarkis 2020) highlighted that the origins of the blockchain as a public system (Nakamoto 2008) are not holding true due to the sensitivity of information.Instead, preferred solutions in SCM seem to be permissioned systems, which can also be joined by competing firms thanks to authorization mechanisms applicable to each node (i.e.user).
Numerous blockchain development platforms emerged recently (Farshidi et al. 2020).Most blockchains for SCM build on either Ethereuman open platform offering also private blockchain solutionsor Hyperledger Fabric, a private modular platform led by Linux Foundation and backed by technology providers such as IBM, Cisco and SAP (Wang, Han, et al. 2019).Efforts of leading enterprise resource planning (ERP) vendors to integrate blockchains into their systems spurred the technology's diffusion across SCs by providing enhanced interoperability between company information systems (Nandi et al. 2020).

Relevant literature and research gaps
Scientific blockchain research in SCM is still at an early stage.The first articles were published in 2016.The current debate includes reviews that cover publicly reported examples (e.g.Chang, Iakovou, and Shi 2020), theoretical elaborations (Schmidt and Wagner 2019), expert studies (Schlecht, Schneider, and Buchwald 2021;Kopyto et al. 2020), and surveys involving SC professionals (Fosso Wamba, Queiroz, et al. 2020).Empirical evidence on real-life blockchain applications is still limited (e.g.Gurtu and Johny 2019), with some case study research being published in the last couple of years (e.g.Moretto and Macchion 2022;Brookbanks and Parry 2022;Danese, Mocellin, and Romano 2021;Rogerson and Parry 2020).Overall, previous research has mostly dealt with agri-food SC solutions (Srivastava and Dashora 2022;Menon and Jain 2022;Vu, Ghadge, and Bourlakis 2021;Chang and Chen 2020).More recently, interest on the performance implications of the blockchain has been growing, considering stock market reactions upon new project announcements (Liu et al. 2022; Kl€ ockner, Schmidt, and Wagner 2022) as well as the effects on operational and sustainability metrics (e.g.Khan et al. 2022b;Tawiah et al. 2022;Hong and Hales 2021;Upadhyay et al. 2021).
A comprehensive review of this growing body of knowledge is outside the scope of this paper.In the next paragraphs, we will thus focus on those streams of research that are more relevant for our RQs, namely blockchain SCM-specific setups (RQ1) and contingent factors affecting their choice (RQ2).
Given the pervasiveness of the technology (Ozcan and Unalan 2022), the first academic efforts towards the identification of SCM-specific setups were directed at the analysis of potential application areas.
Relevant ones include product/material tracking and tracing, SC finance, logistics and delivery (Chang, Iakovou, and Shi 2020), document signing, escrow services and smart contracts (Durach et al. 2021;Dutta et al. 2020), verification of customer reviews and loyalty programs (Durach et al. 2021), digital product management (Dutta et al. 2020), and platform-supported operations (Cai, Choi, and Zhang 2021).In this respect, previous studies highlighted that the most common use of the blockchain for SCM are indeed related to increased visibility over multiple tiers, in particular in terms of product/material trackability and traceability (Nandi et al. 2020;Hastig and Sodhi 2020;Rogerson and Parry 2020).In fact, it has been argued that blockchains have several advantages over traditional SC information systems such as electronic data interchange (EDI) and supplier portals.These advantages include direct communication between all network participants instead of multiple, disconnected, one-toone interactions or communication through a central node (Falcone, Steelman, and Aloysius 2021).Moreover, as blockchains provide the ledger to all participants as a single source of truth (Wang, Han, et al. 2019;Chang, Iakovou, and Shi 2020) there is no single point of failure, as the information stored is immutable and can only be updated through the network consensus mechanism (Fosso Wamba, Kala Kamdjoug, et al. 2020;Dutta et al. 2020).Blockchains thus facilitate the sharing of information beyond the dyadic buyer-supplier relationship and simplify the auditability of records by third parties.Moreover, the need for intermediaries can be reduced thanks to the transparency and immutability of blockchain data (Durach et al. 2021;Cole, Stevenson, and Aitken 2019).It has also been argued that blockchains seem to be more reliable in linking digital and physical flows in combination with other technologies such as the Internet of Things (IoT) (Rao et al. 2021;Chang, Iakovou, and Shi 2020;Kopyto et al. 2020;Azzi, Chamoun, and Sokhn 2019).Against these potential benefits, the literature also documented some drawbacks that seem to hold back the diffusion of the technology.These are a substantial initial investments for integrating pre-existing information systems, operation costs, energy consumption, transaction time (longer than in centralized systems), low technological maturity, lack of international legal and regulatory frameworks, and limited knowledge of blockchain opportunities among SC managers (Schlecht, Schneider, and Buchwald 2021;Kopyto et al. 2020).
Under this premise, the studies that so far have dealt more deeply with SCM-specific blockchain setups can be classified into two main categories.On the one hand, the papers that adopt a technology-based perspective, where the investigated topics are mostly related to type of platform, consensus algorithms, programming languages, accessibility, and storage applications (Kim et al. 2022;Jabbar et al. 2021).In this respect, some studies also propose frameworks for blockchain technology evaluation and selection (Bai and Sarkis 2020;Gourisetti, Mylrea, and Patangia 2020;Farshidi et al. 2020).
On the other hand, research has started to investigate the issue from an organizational perspective, under the assumption that the blockchain is bringing substantial changes in inter-organizational processes and governance, including cooperation and coordination mechanisms (Gligor et al. 2022;Lumineau, Wang, and Schilke 2021).These studieswhich are the most relevant to the aims of our paperhave highlighted some dimensions that are useful to distinguish between different kinds of possible setups.Alongside the technological aspects, Oh, Choi, and In (2022) conceptually define strategic and governance variables that determine different approaches to blockchain projects.The first set of variables refer to value creation and appropriation pattens, the second one to the actors to be involved and the rules of engagement, including data accessibility, control, and decision rights.From a strategic point of view, Malhotra, O'Neill, and Stowell (2022) analyze well-known blockchain projects to derive a typology of adoption models.These models consider the business objectives of the company/consortium initiating the blockchain project and the kind of actors that are involved, i.e. companies along a firm-specific value chain or within an industry-specific/cross-industry ecosystem.Ostern, Holotiuk, and Moormann (2022) highlight that companies have different approaches according to the objectives that drive them into blockchain implementation.Similarly, the case study analysis in food SC visibility of Rogerson and Parry (2020) show that the motivations are key determinants of system choices, including what kind of data (i.e.individual product vs. batch data) are processed.Danese, Mocellin, and Romano (2021) examine applications to prevent counterfeiting in the wine industry, classifying their evidence based on the portion of the SC that is involved (upstream vs. downstream), data feeding and reading, as well as the option to make the data accessible to the final customer.Overall, even though these studies have started to shed light on possible dimensions for identifying SCM-specific blockchain setups, there is still the need for a deeper understanding of their characteristics and conditions for their application.
Regarding academic research on contingent factors affecting the choice of SCM-specific blockchain setups (RQ2), recent literature reviews (e.g.Kayikci et al. 2022;Chang and Chen 2020) have highlighted the need to shed light on the contextual elements affecting not only the intention to adopt the technology, but also on its implementation modes.In fact, the focus of previous academic efforts has been on the identification of drivers and barriers for companies to first leverage the blockchain (Kopyto et al. 2020;Kouhizadeh, Zhu, and Sarkis 2020;Saberi, Kouhizadeh, and Sarkis 2019), so that the actual characteristics of the initiatives that are implemented across the various contexts remain mostly unexplored (Fosso Wamba and Queiroz 2022).Some contingent factors have been mentioned in previous case study research (e.g.Moretto and Macchion 2022;Ali et al. 2021;Hastig and Sodhi 2020;Rogerson and Parry 2020); however, these papers are again focussed on the adoption phase and in most casescollect evidence for companies operating in a single industry.
For the purpose of our research, it is nonetheless important to recognize the contextual dimensions that have been previously highlighted.First, the general environment might play a role in terms of institutional pressures (e.g.norms and regulations) and market demands (Hartley, Sawaya, and Dobrzykowski 2022;Ali et al. 2021;Hastig and Sodhi 2020).
Companies might be more prone to join blockchain initiatives in industries characterized by common pressures/ demands (Kouhizadeh, Saberi, and Sarkis 2021), which might drive network effects that are key for a successful application (Rogerson and Parry 2020).
Second, the literature highlights the presence of productrelated contingencies, especially in terms of product value, price, and market positioning (e.g.Moretto and Macchion 2022;Vu, Ghadge, and Bourlakis 2021;Rogerson and Parry 2020).Further peculiarities emerge as far as the need to ensure traceability of raw materials as opposed to ensuring visibility on components or final products (Danese, Mocellin, and Romano 2021;Hastig and Sodhi 2020).
Third, several studies have stressed the need to consider the characteristics of the supply chain.Here the most important factors seem to refer to SC complexity in terms of number of tiers and firms operating at each tier (Kshetri 2022;Vu, Ghadge, and Bourlakis 2021;Hastig and Sodhi 2020).Further elements include the level of transparency and collaboration among SC partners prior to the introduction of the blockchain (Agi and Jha 2022;Nath et al. 2022;Khan et al. 2022a), the degree of control exerted by the focal firm over its SC (Gligor et al. 2022), the technological maturity, geographical background and organizational cultures of SC partners (Kouhizadeh, Saberi, and Sarkis 2021;Falcone, Steelman, and Aloysius 2021).
In conclusion, several contextual factors seem crucial to understand the adoption of blockchains in SCM, but there is still limited understanding of their influence on blockchain setups and implementation patterns.To address this issue, this study builds on the Contingency Theory of organizations (e.g.Donaldson 2001;Lawrence and Lorsh 1967).The theory postulates that there is no best way to manage a company as strategies and actions depend upon the situation of the firm, both in terms of internal and external factors.Since its earlier elaborations, considerations around technology have been central to the debate (Tosi and Slocum 1984;Jelinek 1977).It has been moreover often applied as far as technology adoption, governance, and as far as performance implications are concerned (e.g.Hsu and Chen 2004;Sambamurthy and Zmud 1999).Overall, the literature has amply confirmed the need for an alignment between firms' strategic objectives and technological solutions (e.g.Mikalef et al. 2015;Raymond and Bergeron 2008); whereas the influence of the external context seems strongly dependent upon the specific technology (Søgaard et al. 2019).

Research method and sampling
Considering that blockchain research is still in its early stages and our aim of theory building on specific setups of blockchain projects, we adopted a multiple case study method (Eisenhardt 1989;Voss, Tsikriktsis, and Frohlich 2002).Such a qualitative-empirical approach can add to the mostly conceptual literature base available (Durach et al. 2021) and is particularly useful for studying complex phenomena and their real-world context (Voss, Tsikriktsis, and Frohlich 2002).Kouhizadeh, Zhu, and Sarkis (2020) highlighted that the multiple case study method is particularly suitable to shed light on blockchain setups in use and their (intended) benefits.Moreover, this method allows to collect and utilize multiple data sources that can be triangulated to develop a broader and more nuanced explanation about the phenomenon of interest.
The unit of analysis of our study was the firm using blockchain for tracking and tracing material flows and product paths along the SC (Hastig and Sodhi 2020;Rogerson and Parry 2020) or providing technical or strategic/operational consultancy on blockchain.
To achieve our research objectives of identifying a holistic set of blockchain SCM setups and related contingent factors, we adopted a theoretical maximum variation sampling method (Eisenhardt 1989;Yin 2018).As suggested for example by Yin (2018) the sampling is based on an a priori expectation that different case characteristics will lead to different blockchain SCM setups.Therefore, we selected heterogeneous cases in terms of industry (automotive, aircraft manufacturing, food, and retail), aim/application (materials tracing, parts tracing, and logistics/data integration), and blockchain orientation (multi-tier upstream, multi-tier upstream þ downstream, dyadic upstream, and internal).Furthermore, in order to have a more detailed picture, we interviewed both blockchain users (cases 1-4) and blockchain service providers (cases 5-6, i.e. a service provider building data and architecture standards for SCM blockchains and a consultancy company supporting firms in adopting blockchain solutions).
Table 1 reports the main features of the sample (using code names to protect identity).Despite our effort to include projects with different levels of maturity, consistently with previous studies (see e.g.Kouhizadeh, Zhu, and Sarkis 2020), 4 out of 6 cases were still at a pilot stage.

Data collection and analysis
Data were collected through a total of nine semi-structured interviews with executives and blockchain professionals (conducted from February 2020 to March 2021).The third column of Table 1 identifies the number and position of the interviewees per case.Interviews were recorded, transcribed, and re-checked by the interviewees.Aligned to the RQ, the interview protocol focussed on three parts.The first part addressed firm's industry, products, and SC characteristics (e.g.power distributions, structural characteristics, and digitalization level).The second part focussed on the blockchain motivation and setup.Questions mainly revolved around blockchain goals, partners involved (and related write and read rights), type of data collected, and integration with other technologies.The third part dealt with the evolution of the blockchain setup over time.The full interview protocol can be found in Appendix 1 (Supplementary Material).For each case we also collected a wide set of archival data both from the interviewees and from public sources (e.g.presentations, reports, website texts) to allow triangulations of results.
Data were then coded and analysed by means of a combination of deductive and inductive qualitative content analysis (Mayring 2010) that enabled a rule-governed and inter-subjectively replicable structuration of the interviews to fully identify the commonalities and differences of the six cases.To achieve this, the coding units encompassed minimum one sentence and up to entire paragraphs if they elaborate the same line of thought as suggested by Mayring (2010).This categorisation of the material was done manually and supported by the software MAXQDA that enabled the association of categories and text passages, their storage and retrieval.No automatic categorisation or analysis was applied.
In view of the explorative character of the RQs and the combined deductive-inductive approach of the study, the coding structure was built and refined in multiple iterations as suggested by Mayring (2010).First, a preliminary coding structure was developed from the literature-based interview questionnaire sections and questions.This preliminary version transformed the central terms of the interview questions into key 'dimensions of analysis' (Mayring 2010, 61), such as blockchain benefits (questions 7, 9, 10 in Appendix 1, Supplementary Material) or product characteristics (questions 1 and 2 in Appendix 1, Supplementary Material) for example.Second, these dimensions were inductively filled by identifying and codifying key contents across the interviews by means of open coding.This led to the definition of for example different benefits such as enhanced availability of information (material origin, inventory levels, etc.) and product value as one of the core product characteristics.Third, the codes were refined by means of axial coding to achieve a balanced and distinguishable representation of the dimensions of analysis such as distinguishing high and low product values and linking this to concrete examples.This refined coding system was then applied to all interviews to achieve a full coding of the cases.Finally, a pattern matching process was conducted to identify and interpret specific code combinations and their relation (Eisenhardt 1989;Voss, Tsikriktsis, and Frohlich 2002), as presented in the analysis and synthesis sections.

Validity and reliability
In the study design, data collection and analysis, we adopted a set of strategies to enhance construct validity, internal  (Yin 2018;Eisenhardt 1989).We triangulated empirical evidence from different sources (i.e.interviews and archival data) and multiple respondents (whenever possible) to ensure construct validity.Internal validity was then achieved by pattern matching of the content categories across the cases and reliability is ensured by case study documentation, basing the content analysis on a well-defined as well as iteratively refined codesystem, and involving multiple coders in content analysis (Yin 2018;Mayring 2010).

Within-case analysis
Within this section, the six cases and their details relevant for the RQs are outlined.To enable a better comparability, all cases present in the first paragraph a brief summary of firm data as well the core product and aims addressed in the blockchain project.The second paragraph illustrates the characteristics of the blockchain project, then we provide evidence regarding an outlook and/or reflection on the blockchain project.

Case 1: Automotive
The case company is a globally active automotive OEM based in Europe.The investigated blockchain project was applied to increase the transparency across its upstream supply network of batteries, their parts, and raw materials with a dedicated multi-tier focus.Main considerations cover enhanced efficiency in capacity planning, quality assurance and sustainability management that encompass the whole multi-tier SC but are hardly matched with integrated information systems.
The blockchain project involved approx.20 partners by the time of the interview, which were all dedicated to achieve in their common SC high quality, performance, and sustainability.This group can be considered relatively homogeneous in terms of strategy and goals, which has been explicitly underlined by the interviewee to be a facilitating factor.He stated: 'For this specific supply chain and pilot project, people wanted to participate, because they do a lot of things for sustainability, for human rights, for the quality of the product, and so they had no problem to share.[However, … ] if you go for another commodity, this can be really a problem' (automotive case interviewee 1).Due to the interconnectedness of the automotive sector, the project applies a consortium blockchain approach that is actively encouraging competitors to join and create efficiency gains in supplier certification and monitoring.Each partner is free to restrict the transparency of its data within the consortium to safeguard competitive information.
For the future, efficiency gains based on the growing amount of data are aimed for but have not been realized at the time of the interview.These gains are expected to arise from shared information of supplier audits as well as easier and shared documentation and verification of raw material origins.

Case 2: Aircraft manufacturing
The case firm is a major aircraft equipment manufacturer for which the blockchain is the backbone of an online marketplace for used and new aircraft parts, which by law have high documentation and quality requirements.
Within the blockchain project, the case firm captures as much documentation as possible on materials, parts' manufacturing, use and maintenance to build a part pedigree.To enable this, the firm's ERP system is integrated with the blockchain, so that any part produced and later inhouse service to this part can be taken into the blockchain to support the part's value and fight counterfeit.In effect, parts related data is shared in the blockchain.Other partners across multiple tiers of the SC such as aircraft repair shops or dismantlers are permissioned into a consortium blockchain to cover a rising share of the aircraft part maintenance, repair and dismantling sector, thus enabling eventually a fully digital aircraft parts documentation.Beyond the consortium blockchain in which all members have write access, the project enables restricted read permissions to any customer.This customer read access is limited to individual parts in the marketplace.As a result, this cumulation of offers and their characteristics in one blockchain-enabled platform enhances the efficiency of aeroplane maintenance in comparison to the previous need to compare offers across different suppliers and requesting individual information on parts' origin and quality.All other blockchain entries remain visible exclusively to the consortium thus reducing the information asymmetry of blockchain members and their customers only in case of potential sales.The case firm puts particular emphasis on sustaining transparency of part pedigree and parts quality of the high-value technological products produced and sold by them.In the sales phase, this blockchain project enables the verification of part originality and quality.If the parts are not in the marketplace, their information is restricted to the consortium to enable data analysis and value generation only for the involved partners and not the public or competitors.This value can be drawn from analysing for example average live spans and failure reasons of aircraft parts in different conditions.
Future developments of the blockchain project focus on generating revenues and cost savings for the case firm as the central actor of an ecosystem centreing on the valorization the collected data.The interviewee underlines: 'I can guarantee that once you start building out the part pedigree, lots of other companies can find different ways to build applications or different services on top of that valuable data, to figure out how it brings value and benefits to the integrated supply chain.Whether it's like … anti-counterfeit technologies, whether it's parts tracking, there's lots of different ways in which you can leverage that data and this technology to bring value to multiple facets of the supply chain' (aircraft manufacturing case interviewee 1).

Case 3: Food
The interviewed company is one of the largest diversified US based food suppliers serving more than 100,000 restaurants with (compared to the previous cases) low value but highvolume supplies that are often perishable.This leads to substantial potentials in reducing food waste and optimizing logistics efficiency, which are aimed to be realized through a blockchain.
The investigated blockchain project aims to realize these potentials by leveraging on the 'natural intersection between the blockchain capability to be an umbrella over a system or a number of ERP systems and be the source of data.It's really like a database' (food case interviewee 1).The project objective is to substantially enhance the speed and responsiveness of the transaction conduct and planning of the perishable products.Therefore, the consortium type blockchain covers multiple tiers of a single product SC and captures operational information like stocks, material flows and some perishability-related data, i.e. quality, features.The interviewee highlighted that reduced cost is the shared benefit serving the self-interest of the partners.To safeguard any kind of sensitive information, this blockchain allows each partner to define for the individual sets of its data which other partner may read them.Generally, the case firm sees high potential for blockchain applications in the downstream food SC that is often dominated by large food producers, retail or restaurant chains and their complex production and logistics networks.Contrastingly, the dispersed and much smaller upstream suppliers like farmers and cooperatives are expected to be harder to convince and integrate for reasons of absent or heterogeneous IT infrastructures.This is also seen as a barrier to full transparency down to the single piece of meat or corn.
Further steps in this blockchain project consider the fact that the link to the business customers is already well developed and future potentials mainly lie in upstream efficiency gains.To enable more upstream efficiency, the project is aimed at connecting more suppliers to the systems.This is planned in a step-wise approach from one tier to another to eventually enable 'tracing it all the way back to the rancher that raised the beef' (food case interviewee 1).

Case 4: Retail
The retail case is a blockchain proof of concept involving major US retailers and global brands of suppliers.The project focuses on consumer goods production, logistics, and sales supported by Radio-frequency identification technology (RFID).
In essence, the blockchain collects RFID generated data from the case firm's suppliers into a single record to secure the SC from counterfeited products and reduce claims management and reconciliation efforts.A central means to that end is the establishment of a unified standard on the content of data collection and storage, that is envisioned to be realized through a blockchain.The project responsible underlined that 'the ability to have a shared distributed ledger where I have one version of the truth and data … , is the single biggest benefit' (retail case interviewee 1).This system integrates different ERP and EDI systems.Beyond the proof of concept, the required roll-over of legacy ERP systems is seen as a major challenge since most managers fear to reveal too much of their data in a fully integrated ERP environment.A blockchain is thus seen as an attractive solution as it offers the potential to link the heterogeneous IT systems by collecting a reduced set of operational data thus reducing information asymmetry in the SC.The blockchain project is thus aimed at 'creating an industry platform for the ability to update on things that are going on in the supply chain, so everybody has that single version of the truth' (retail case interviewee 1).At the same time, the restriction of read access to close partners in the SC is underlined in this case as well.
Looking into the project's future, the clear expectation is that a standardized set of high-quality operational SC data will yield benefits like reduced stocks, quicker replenishment, and reduced waste of perishable or outdated products.However, the interviewees underline that the implementation will require much more effort since for such an integrated SC IT innovation 'there is not really a precedent for how we do that' (retail case interviewee 2).

Case 5: Blockchain standards and service provider
Beyond the SC oriented pilot projects, we also interviewed two experts of a large US standards and service provider that is actively trying to build data and architecture standards for blockchains in SCM.Their work and expertise are cross-sectoral and they provided a more general perspective on the topic by reflecting on their work with different customers as well as in roundtables and blockchain councils.
Interestingly, the interviewees underlined the ongoing quest for standards in how to share the data and defining shared contents for the blockchain.This is seen as 'the only way that blockchain is ever going to be scalable, if these different [blockchain] solutions decide upon using one standardized language.[Since otherwise … ] it doesn't matter that I have access to more information, if I have no idea what it means' (blockchain standards and service provider interviewee 2).Moving beyond the mostly technological perspectives on blockchain architectures, they highlighted the relevance of market forces as the expected main determinant of what blockchain setup in terms of shared contents as well as who has read and write access will eventually prevail.In contrast to a public blockchain and its aim of enhanced visibility, also the blockchain experts in this case reiterate the need for reduced visibility even in consortium blockchains, so that competitors cannot access any data of each other.So, comparing publicly debated promises of blockchains that mainly refer to Bitcoins and envisioning all these promises in SCM, the SC blockchain experts state 'I don't know that this happens or if that needs to happen, but I think a practical [blockchain] implementation is very different than what you see in Bitcoin and things like that (blockchain standards and service provider interviewee 2).They underline that this does not necessarily enable a major step forward from current information sharing systems that are seen capable of fulfilling most of the tasks envisioned for the blockchain without the need for implementing a new and costly system.In line with the previous cases, the interviewees see current business cases in high-value products through transparency and anti-counterfeit over multiple tiers.For lowvalue products it might be too difficult and costly to implement a full blockchain.Nevertheless, the blockchain characteristics of immutability and (almost) real-time data availability are seen as valuable for low-value products as well in lowering claims management costs.
The further work of the case firm regarding blockchains in SCM, is the creation of more work groups to distil industrial needs and consult the creation of related solutions using blockchain or other technologies, since 'it's a slow move and [ … ] there's a lot of hype, a lot of misunderstanding' (blockchain standards and service provider interviewee 1).

Case 6: Strategic consultant
Finally, we interviewed two experts of a consultancy company that supports firms in the implementation of blockchain projects in diverse environments.In the interviews, we focussed on a project for inventory monitoring in a corporate group with multiple independent units that need to provide an integrated inventory (financial) report.
The blockchain in this project was intended to automatically capture and immutably store operational data like stocks along other assets of the units.The data was taken from the units' ERP systems.Despite the common ownership of the units, the interviewees underlined the fact that even in such cases there is a heterogeneous set of IT systems in use for which the blockchain is intended to provide an integrative solution for a reduced set of data.In effect, 'the information would be pulled automatically from the different systems and then the reconciliation process has been done in the digital blockchain tool and the employee just had to confirm that transaction' (strategic consultant interviewee 2).The main objective is a real-time data sharing for facilitated toplevel decision making as well as quicker and less costly reporting and reconciliation.This is seen as a major advantage over often poorly standardized data collection via mail or phone that was used before.The interviewees underlined that such an automated data sharing platform will build a business case due to lowered costs.It was highlighted that shared databases would also be suitable and less costly than blockchain solutions that are seen as 'a costly database that [ … ] in the end ensures trust in the data' (strategic consultant interviewee 2).However, the blockchain hype is attracting firms even for intra-organisational applications in which trust issues should be less relevant.Although the focus is currently exclusively intra-organizational, the interviews reaffirmed implementation barriers of lacking clarity and understanding of blockchain characteristics and benefits as well as privacy and competitiveness concerns regarding information sharing.Despite the different focus, these challenges are similar to inter-organizational applications.

Cross-case synthesis and discussion
This section synthesizes the findings across the cases and discusses them against current literature to create three sets of propositions and one matrix that can guide future practical and academic work.We first identify four blockchain setups based on the addressed traceability/trackability drivers (perceived customer value vs. efficiency improvement and cost reduction) as well as focus (product-oriented vs. raw material-oriented).Regarding the adoption of the four setups, we then elaborate three sets of contingent factors related to the general environment, the product, and the SC.Finally, we discuss emerging patterns regarding potential evolutions of the initial blockchain setups.We present these three topics in the following sub-sections.

Defining the blockchain setup based on traceability drivers and focus
Our interviews revealed that an important factor determining the blockchain setup refers to how the company or consortium approaches the issue of traceability/trackability. We identified two key dimensions in this respect.The first refers to the traceability/trackability drivers, meaning whether blockchain adoption stems from external pressures (i.e.regulations, standards, customer demands) or rather from internal needs (i.e.inventory optimization, waste reduction).The external pressures focus on the scrutiny of a product's characteristics, which are leading to enhanced customer perceived value.The internal needs instead aim at the efficient exploitation of the processes to realize efficiency improvement and cost reduction.The second dimension investigates the focus of the blockchain setup, being either the final product or the raw material origins.Figure 1 presents a matrix that elaborate these two dimensions, yielding four blockchain SCM setups.From our cases we can populate all setups of the matrix but one, which is seen as not economically viable at present, as underlined by case 5 and elaborated below.
Starting from the first dimensiontraceability/trackability driversour cases can be distinguished by an initial motivation related to either the opportunity to gain enhanced customer perceived value (automotive and aviation cases) or to pursue efficiency improvement and cost reduction (food and retail cases).These might influence the blockchain setup in terms of access and reading rights.Most cases support the following statement of the automotive case: 'we have no use case in our industry where you have a permissionless blockchain' (automotive case interviewee 1).Nevertheless, it is possibleas shown by the aviation blockchain operating a marketplaceto grant restricted reading access for customers outside the consortium.This is achieved by verifying the aviation part's origin and qualityas prescribed by lawfor example by means of a single verified record in the blockchain.This access enables the reading of parts of the data related to a single object in the marketplace to support the compliance to external traceability needs and market demands focussing the product's customer perceived value.This example is in line with other initiatives thatbased on external demands for higher visibility on the product characteristicsgrant reading access (e.g.MOBI.2021).Vice versa, whenever the blockchain is applied following internal efficiency improvement and cost reduction needs, there is no need to make the information accessible outside the company or consortium.Among our cases, the food and retail case do not apply the blockchain to comply to any regulation or external demand but define internally what product data needs to be captured in their blockchains to enhance operational efficiency in the exploitation of their SC processes.
The second dimension refers to the project's focus.Beyond the product-oriented trackability/traceability in the aircraft, food, and retail cases, the automotive case exercises compliance in its upstream SC revealing a raw material-oriented traceability.The latter relates to supplier audits against common standards that are currently done redundantly by multiple automotive OEMs individually, thus offering potential for efficiency gains through sharing the audit results.Beyond the cases presented here, the same efficiency potential regarding redundant audits is evident for example in the upstream parts of the textile SCs (Huq and Stevenson 2020;Sauer, Silva, and Schleper 2022).
Based on the combination of the two dimensions, we identify the four blockchain setups presented in Figure 1 that are setup 1: product-oriented compliance related to the aviation case, setup 2: raw material-oriented compliance related to the automotive case, setup 3: product-oriented efficiency which is explicated by the retail and food cases using  RFID enabled tracing, and setup 4: raw material-oriented efficiency.The latter setup is however not represented by the investigated cases since it is hardly economically viable as a standalone setup.In fact, the interviewees report, in line with literature (e.g.Schlecht, Schneider, and Buchwald 2021;Kopyto et al. 2020), that operational data on the raw materials side in their SCs is either poorly documented or data integration is difficult due to heterogeneous ERP systems and data formats.The retail case details this by stating what we found was we were getting in all these different data streams.I think it was like 35 different data streams, each in a different format and so it was like we're getting everything in.But you know, we can't really use this RFID data because it's so specific to that one point in the supply chain.(retail case interviewee 2) Setup 4 seems thus hard to apply because of a difficult definition of traceability needs as well as substantial investment and training requirements that potentially outweigh the blockchain benefits.Similar limitations need to be considered for setup 3: product-oriented efficiency.In a similar vein, the food case underlines that it does not make sense to include partners that do not share the same traceability need and that a very high number of farmers will be required to create the initial data sets.This can be linked to the challenge of diverging awareness and understanding (Fosso Wamba, Kala Kamdjoug, et al. 2020), regarding which the aviation interviewee reassures that if she asks what people think blockchain is … I guarantee you that you'll get a different answer from each of those people.(aviation case interviewee 1)

Raw materials Focus
Consequently, challenges of lacking technological infrastructure and lacking or diverging standardization across the wide supplier base are foreseen.Moreover, raw materials tend to have a relatively limited value per unit for which suitable blockchain applications are found to be limited as well.Focussing on raw materials' value and its efficient exploitation by means of optimized logistics, we expect that this will more likely be achieved by large firms, while it might be beyond the scope of an average farm and its often limited logistics operations.
Reflecting these challenges, it becomes evident that the setups 1 and 2 benefit from reduced data-related challenges, since they can rely on an external definition of which data are to be captured to comply to the stakeholder expectations.In the other setups, instead, the participating firms need first to define these data and at the same time convince all SC partners of the opportunities to collect and share them.These actor-related challenges differ between the product-oriented setups 1 and 3 on the one hand and setups 2 and 4 on the other.The former setups are facing the challenge of motivating downstream SC partners to join the blockchain before the system's benefits can be realized based on overcoming a critical mass of data entries.The latter setups include suppliers that see the strong need to safeguard their competitive information on process performance and their own (sub-)suppliers' identity.Additionally, the blockchain's benefit will be realized at the downstream SC end, while extra effort is required at the upstream SC partners.This tension needs to be addressed in setups 2 and 4.Moreover, the driver of efficiency improvement and cost reduction is to a certain degree linked to a critical mass of process steps and product volumes to realize sufficient benefits.However, there is also an upper limit of data traffic that a blockchain can handle while realizing near real-time data visibility in order to not overburden the system.
These considerations lead us to formulate Proposition 1: P1: Traceability/trackability drivers and focus define four distinct blockchain setups.
P1a: Setup 1: product-oriented compliance supports the realization of an enhanced costumer perceived value by using a blockchain in SCM focussing the SC's products/components.
P1b: Setup 2: raw material-oriented compliance supports the realization of an enhanced costumer perceived value by using a blockchain in SCM focussing the SC's raw materials.
P1c: Setup 3: product-oriented efficiency supports the realization of an efficiency improvement and cost reduction by using a blockchain in SCM focussing the SC's products/components.P1d: Setup 4: Raw material-oriented efficiency supports the realization of an efficiency improvement and cost reduction by using a blockchain in SCM focussing the SC's raw materials.

Understanding the contingent factors affecting the choice of a setup
Diving into the details of how the individual blockchain setups are applied in our cases, it becomes evident that the choice of a setup is contingent on three main factors displayed and detailed in Table 2: general environment, product, and SC.
Starting with the general environment, we see that the investigated blockchains are created in response to either external or internal stakeholder pressure.Setup 1 and 2 respond to external stakeholder pressures for compliance of either product or raw materials by building an immutable documentation of their core characteristics.Setup 3 and 4 instead are a reaction to internal pressure for efficiency that is supported by creating real-time visibility of 'one single version of the truth' (retail case interviewee 1) being visible to the relevant blockchain members' partners without any ambiguity in the data.
As far as product characteristics are concerned, we find in our cases that blockchains are mainly used for products with medium to high value per unit.This result is aligned with previous studies (e.g.Chang, Iakovou, and Shi 2020;Falcone, Steelman, and Aloysius 2021;Nandi et al. 2020).Moreover, setup 2 is applied to raw materials with high risks especially in the sustainability domain.As mentioned, setup 1 and 2 build an immutable and accessible record of material and component origin, brand, sustainability-related data, and history that supports the value and sales of products with inputs or characteristics that are under stakeholder scrutiny, like conflict minerals (automotive case), jet engines (aviation case), or branded retail products (retail case).Answering to this scrutiny, blockchains can help companies to fulfil regulatory requirements more efficiently by reducing tracing costs for individual items or medium batches, documenting material origins (automotive case) or parts maintenance (aviation case) (see also Durach et al. 2021;Bai and Sarkis 2020).Setup 3 and 4 instead focus on the tracking of individual products or small batches as well as large batches of raw materials.This will result in a standardized and more efficient inter-firm information sharing platform to optimize SC processes.The main aim is to gain real-time visibility of operational process data enabling optimized claims management (retail case), logistics processes and stock levels (retail and food cases) thus reducing operational costs (see also Durach et al. 2021;Bai and Sarkis 2020).
Looking into the third contingent factor of SC characteristics, another distinction became evident.The blockchains are applied to overcome different structural SC challenges.Setup 1 for example is applied to collect the relevant information for individual products across a wide range of independent actors representing a relative fragmented downstream SC.Setup 2 is applied to overcome the challenge of establishing visibility in upstream SCs of raw material and component suppliers across multiple tiers.Such long multi-tier structures typically cause the loss of information due to poor sharing and competing interests of the suppliers (see also Sauer 2021;Zehendner et al. 2021).Setup 3focussing on efficiencyis applied whenever companies serve highly concentrated customers like retail or restaurant chains to provide a single data set enabling optimized operations planning by tailoring the material and financial streams in the SC.Finally, setup 4 could be aimed to respond to the fragmentation of upstream SC supplying mainly commodities for which improved planning and payment processes are envisioned.
Relating key blockchain characteristics to the four setups, these characteristics seem more apt for setup 1 and 2. Immutability for example is key to efficiently trace product characteristics of for example high value products such as their sustainability, origin or brand as well as to reduce counterfeit (e.g.Falcone, Steelman, and Aloysius 2021;Nandi et al. 2020;Chang, Iakovou, and Shi 2020).In contrast, immutability and its computational needs might slow the speed of the information collection and exchange of complex processes that is aimed for in setup 3 and 4.
From an efficiency perspective that is core to setup 3 and 4, the suitability of complex blockchain applications is limited if they are linked to high production and logistics volumes (as underlined by the retail and food cases) that require substantial computational power for a tracking and tracing via a blockchain.For low value products both setups will come to limits since the required investments face comparatively lower benefits due to low margins.During the interviews, this was underlined by stating: It is, you know, billions of items, multiple read points, you know that there's no blockchain that can do that right now, and even if, it could be really expensive.So yeah, it is really about the volume and the value of the items.(blockchain standards and service provider interviewee 1) Overall, our interviews confirm thatat presentthe blockchain is seen as unsuitable for low-value as well as high-volume products in SCM due to a currently negative costs-benefits balance.This lack of suitability is amplified if individual items are to be tracked or traced since this would multiply the data to be handled.Moreover, high degrees of vertical integration will render the implementation of a blockchain in addition to existing ERP systems futile since the core benefits of a blockchain do not materialize in intrafirm systems.Finally, the resources required to implement and run a blockchain need to be justified against some stakeholder pressure to which the blockchain may be an answer.
These elaborations of the three contingent factors lead us to Proposition 2: P2: The choice of a particular setup for a blockchain in SCM is contingent on the characteristics of the general environment, the product and the supply chain.
P2a: The choice of setup 1: Product-oriented compliance likely is a response to external stakeholder pressure for an immutable tracing of individual products of high value per unit within a fragmented downstream supply chain.
P2b: The choice of setup 2: Raw material-oriented compliance likely is a response to external stakeholder pressure for an immutable tracing of medium size batches of raw materials associated to supply chain risks within a fragmented and multi-tier upstream supply chain.
P2c: The choice of setup 3: Product-oriented efficiency likely is a response to internal stakeholder pressure for real-time visibility of a verified current status of individual products or small batches of them with medium to high value within a concentrated downstream supply chain.
P2d: The choice of setup 4: Raw material-oriented efficiency likely is a response to internal stakeholder pressure for realtime visibility of a verified current status of large product batches with low value per unit within a fragmented upstream supply chain.
While the four setups are presented individually, they are not mutually exclusive and some combinations can be facilitated by SC characteristics like some degree of vertical integration that might span the raw material as well as the product part as also elaborated in the following section.

Evolving initial blockchain setups
Moving beyond the initial setup, several cases highlighted actual or planned evolutions.
A common path seems to be that projects starting from setup 1 or 2 focussing on enhanced perceived customer value covered by externally driven traceability needs would eventually also contribute to efficiency improvement and cost reduction of SC processes covering setup 3 and 4. In the aviation case, permissioned blockchain members can access the data in bulk and eventually draw value from them through more accurate supply and demand forecasts, which would enable enhanced production and logistics efficiency just like we found it in the retail and food cases.Similar considerations are evident in the automotive case that aims for an enhanced capacity management for scarce raw-materials and components in the future.
The other evolutionary path refers to the inclusion of a growing number of companies in the SC, potentially aiming at industry-wide solutions.The retail case interviews underlined that we have a window of opportunity to get this [standardization of data across multiple SC partners] right.If we don't get it right, everybody is going to create their own version and trying to migrate them to a single platform will be nearly impossible.(retail case interviewee 1) Overall, our results echo the concerns over a potential lack of standardization and interoperability among different blockchain solutions that can be adopted for SCM.This might limit the power of the blockchain technology in SCM and needs to be considered by managers and policy makers when they decide to adopt or push a certain solution.
Combining this with a reflection on the potential and promise of the blockchain technology, a full SC coverage in terms of including raw material-oriented as well as productoriented traceability should be aimed for (see also Rogerson and Parry 2020;Kouhizadeh, Saberi, and Sarkis 2021;Bai and Sarkis 2020).This more nuanced and sequential understanding of the adoption of the setups leads us to formulate Proposition 3: P3: Blockchains in SCM starting from setup 1 or 2 focussing on enhanced perceived customer value can benefit from the extension to cover also efficiency improvements and cost reduction drivers (observed in setups 3 and 4).

Conclusions
This study adds empirical evidence to a hitherto mainly conceptual literature on blockchains in SCM (Durach et al. 2021;Agi and Jha 2022;Srivastava and Dashora 2022) and extends related theory in three main ways.
First, we identify four distinct setups for the application of blockchains in SCM depending on the traceability/trackability needs and focus.These setups are characterized regarding their characteristics and challenges which reveal their distinctiveness.This refines a still too unidimensional view of the application of the blockchain technology for tracing and tracking purposes.In fact, the opportunities and limitations of different blockchain setups as means to achieve certain ends are outlined (see Figure 1), allowing for deeper considerations as to implementation challenges and potential performance implications.
Second, although the blockchain has often been regarded in the literature as a mean for multi-tier information sharing (e.g.Kayikci et al. 2022;Bai and Sarkis 2020), the cases in our study were clear that even if more tiers were integrated, the visibility would be mainly limited to the dyad by means of privacy settings due to agency concerns.Consequently, we see that the investigated cases will maybe achieve (a) the suggested SC wide integration but hardly (b) the SC wide transparency with read access for all partners.So, instead of establishing full transparency for all stakeholders right from the outset, as it is often envisioned in literature (e.g.Kayikci et al. 2022;Bai and Sarkis 2020), the blockchain projects at the moment aim at creating a shared platform for existing business partners.The blockchain technology however has the potential to go beyond the restricted transparency if the product, SC and environmental characteristics outlined in Table 2 will sufficiently support this in the future.It can be assumed that rising adoption and maturity of blockchain technology will enable this move towards more transparency.In line with Fosso Wamba, Kala Kamdjoug, et al. (2020), we currently find that this restricted transparency and thus at least partial anonymization is caused by privacy concerns regarding sharing too much information in the consortium.Consequently, blockchain's widely echoed benefit of anonymization is reported to attract partners, at least in the initial implementation phase.
Third and after several iterations of the theory building and refinement discussions among the authors, we were able to align the selection of the four individual setups of blockchains in SCM to three literature-based contingencies that we further elaborated.Moreover, we could order the practical investigation of blockchains in SCM into the three distinct aspects focussing setups, contingencies and evolutionary paths.This supports the practical value and actionability of our findings by ordering the widespread and sometimes fuzzy appraisal of blockchains in SCM.

Managerial and policy implications
In terms of managerial implications, this study offers actionable guidance in the propositions, Figure 1 and Table 2.These shed light on characteristics of product, SC and general environment that are more or less suitable for blockchains in SCM.Moreover, and within contingency theory, the elaboration of specific propositions expands the scope of contingencies relevant in contemporary business practices.By collecting some practical experiences, our cases can be equally useful for managers interested in blockchain technology.The identification of the most important contextual factors can help them in seizing blockchain opportunities, gauge potential roadblocks and structure the relationship with SC partners and competitors.We thus help alleviating some of the many uncertainties in the implementation of blockchains in SCM.
More concretely, managers could use Figure 1 as a blueprint to structure the aims they plan to realize with a blockchain and compare for the characteristics outlined in Table 2 to see if their application context has been found to fit their intentions.Moreover, we want to echo the reflection by case 4 (retail) and 5 (service provider) that there is a current hype around blockchain that is blurring the fact that it is not the silver bullet for any SC challenge (see also Kumar, Liu, and Shan 2020).Instead, ERP systems might well cover some of the intended aims with relatively lower resource requirements and implementation barriers.If managers decide to adopt a blockchain solution it might be beneficial to consider the option to link to other blockchain projects through the use of common data formats and standards to avoid path dependencies that might create barriers towards the adoption of interoperable solutions since resources are bound into the existing projects already.
Policy makers could use our findings to better understand how their pressure to date has built the basis for setup 1 and 2, while a link between the setups and especially to setup 3 and 4 is possible but at the same time dependent on the definition of common data formats (see Figure 1).Our interview partners underline that there is a 'window of opportunity' (case 4 interviewee 1) in which however (too) many competing solutions might hinder a wider implementation.Policy makers could support the industry in this regard for example by supporting certain data standards or moderating the search for more consensus on data formats.Such data standards could drive the combination of setups supporting the aims of both firms and regulators to establish larger up-and downstream SC visibility, i.e. combining the setups on the horizontal axis of Figure 1.In the policy domain this could especially support the compliance to regulation forcing firms to take responsibility for their SC that has been implemented at least for certain sectors in the USA (Dodd-Frank Wall Street Reform and Consumer Protection Act passed in 2010), UK (Modern Slavery Act passed in 2015), and Germany (Lieferkettensorgfaltspflichtengesetz passed in 2021), to name only a few prominent examples.

Limitations and research directions
Beyond its contributions, the study is limited by three main issues that simultaneously can guide future research.First, the suggested propositions, tables and figure deepen our understanding of blockchains in SCM, but they do so only in general terms and using rough scales of 'high' and 'low' or 'product-' and 'raw material'-oriented.Future research could refine and quantify the dimensions and contingency factors by means of additional case studies or surveys.
Second, the interviews are mainly collected in the USA and Europe and might thus be biased to related perspectives and specificities in the business structures.Future research is thus encouraged to realize a more balanced sample to alleviate this limitation.Investigating international and intercontinental blockchain consortiums could be of particular value in this regard.
Third, we acknowledge to rely on a limited number of cases that limits the generalizability of our findings.Nevertheless, we need to underline that the application of blockchains in SCM is still scarce and the interviewees report to face a flood of interview requests.Nevertheless, we deem the inclusion of evidence from more industries and potentially multi-tier interviews with buyers and suppliers from the same blockchain project to be especially fruitful.

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Needs: product quality, i.e. aviation parts age and maintenance (part pedigree documentation), compliance to regulation on documentation of product characteristics (defines also the required data) • Scope: from manufactured product until end of product life • Data-related challenges: definition of data format • Actor-related challenges: creating a critical mass of blockchain participants to realize sufficiently automated documentation and data-Needs: (raw) materials origin and sustainability documentation, compliance to regulation and stakeholder requirements on product characteristics, such as a) the avoidance of conflict minerals in products and b) supplier audits (defines also the required data) • Scope: from raw material to sale of the end-product • Data-related challenges: definition of data format • Actor-related challenges: supplier training to achieve sufficient data quality and protection of suppliers' competitive information on a) operational performance margins and b) sub-supplier identity Needs: enhance efficiency of focal firm over controlled SC processes in terms of product stock, demand, quality • Scope: from manufactured product until retail • Data-related challenges: definition of required data and data format • Actor-related challenges: creating a critical mass of data entries for holistic process optimization while not overburdening the blockchain system Setup 4: Raw material-oriented efficiency No cases found.

Table 1 .
Overview of case studies and data collection.

Table 2 .
Overview of contingent factors affecting the choice of a particular setup.