Mikołaj Barczentewicz joined the School of Law in 2017. His research spans technology law and policy, applications of technology in legal practice and research, UK and EU public law, and legal philosophy. Mikołaj approaches those topics combining traditional methods of law and philosophy with computational methods, building on his experience as a professional computer programmer.
Mikołaj is also a Research Associate of the University of Oxford Centre for Technology and Global Affairs, a Research Associate of the University of Oxford Programme for the Foundations of Law and Constitutional Government, and a Fellow of the Stanford Law School and University of Vienna Transatlantic Technology Law Forum.
Before joining Surrey, Mikołaj taught law at the University of Oxford. He was also a Visiting Scholar at the University of Melbourne. Mikołaj is a Fellow of the Higher Education Academy.
Mikołaj published in the Oxford Journal of Legal Studies, Modern Law Review, Law Quarterly Review, Public Law, Connecticut Law Review and in other journals and edited collections (for details see his personal website).
Areas of specialism
Postgraduate research supervision
- Ethics and Regulation of Artificial Intelligence
- Privacy and Data Governance
- Law and Technology
Modules taught previously:
- European Union Law
- Public Law
Cart judicial reviews constitute the largest single group of claims for judicial review in the High Court. However, they are difficult to study because they rarely result in a High Court judgment and thus are reflected in the popular case law databases. I analysed the best public source of information on the fate of successful Cart judicial reviews—Upper Tribunal decisions following successful Cart claims from 2018 to 2020 selected programmatically from a dataset of over 42,000 — mostly unreported — decisions. Thus, I can discuss the key aspects of successful Cart challenges, including the question what claims succeed in meeting the ‘second-tier appeals’ test for permission set in CPR 54.7A(7). This study complements the previous quantitative study on rates of success in Cart and non Cart judicial reviews and contributes to the broader discussion on the appropriateness of retaining the Cart procedure in the context of the proposal to discontinue Cart claims made by the Independent Review of Administrative Law and adopted by the Government in the Judicial Review and Courts Bill.
The paper offers a reflection on how applications of computer technology (including data analytics) are and may be taught to (future) lawyers and what are the benefits and limitations of the different approaches. There is a growing sense among legal professionals and law teachers that the technological changes in the practice of law are likely to promote the kind of knowledge and skills that law graduates often do not possess today. Teaching computer technology can be done in various ways and at various levels of depth and that those different ways and levels have different cost and benefit considerations. The paper discusses four models of teaching technology: (1) teaching basic technological literacy, (2) more advanced but general technology teaching, (3) teaching computer programming and quantitative methods and (4) teaching a particular aspect of technology – other than programming (e.g. cybersecurity). I suggest that there are strong reasons for all current and future lawyers to acquire proficiency in effective uses of office and legal research software and standard means of online communication and basic cybersecurity. This can be combined with teaching of numerical and informational literacy. I also claim that advanced technology topics, like computer programming, should only be taught to the extent this is justified by the direct need for such skills and knowledge in students’ future careers, which I predict to be true for only a minority of current lawyers and law students.
This chapter provides a critical overview of the debate on the relationship between precedent making and exercises of a particular kind of legal powers: law-making powers. In doing so, it challenges some common claims about the courts (necessarily) having law-making powers. The chapter discusses what is common among the major general accounts of legal powers and shows the role of intentions and of volitional control of power holders. Those aspects have consequences for what kind of judge-lead legal change should be viewed as an exercise of a legal power specifically to make (change) the law. This is particularly salient in cases of ‘unprecedent’ (where a court tries to avoid setting a precedent) and to situations where court-led legal change becomes effective through a mechanism akin to custom than to legislating. Moreover, the chapter discusses the question of the tension between the official stories (ideologies) of legal systems and second-order (e.g. academic) accounts on the issue of judicial powers to make the law. It argues that one should not be too quick to dismiss the law’s official claim that judges do not have a power to make the law.
On public, permissionless blockchains like Ethereum, space is scarce and crypto traders must compete to use it for executing their transactions. That means those who control this space in the form of blocks resemble landlords who can extract rent. “Maximal Extractable Value” (MEV) refers to trading strategies that exploit the ability to decide what transactions go into a block. Those who control the contents of a block (validators) can obtain rents not only for including transactions in a block, but also for ordering them in profitable ways—say, by letting transactions “front-run” others. Since rising to prominence in 2019, MEV has quickly become a major market phenomenon, generating $600 million in profit between 2020 and 2022 alone, while affecting tens of billions of dollars in transaction value. MEV is often condemned. Techniques like “sandwich attacks” which involve trading ahead of other users' trades, have been described as toxic, fraudulent, manipulative – even theft. However, this broad denunciation of MEV is too quick, as the technical nuances of how each kind of MEV extraction operates are determinative of the legal risk it entails. The legality of MEV extraction under U.S. financial laws has yet to be subject to sustained scholarly analysis, and the present Article aims to fill this gap. We undertake the first systematic analysis of how U.S. securities and commodities law, particularly the broad anti-manipulation rules wielded by the SEC (Rule 10b-5) and CFTC (Rule 180.1), apply to core MEV extraction techniques on Ethereum. In so doing, the Article confronts how basic notions of fairness and trust play out differently in a world of discretionary transaction ordering in crypto markets compared to the first-come first-serve world of traditional finance. Behaviors that might seem outrageous off-chain look very different when examined in light of how blockchains actually work. Nonetheless, this Article argues that some forms of MEV extraction entail a significant risk of market manipulation liability. Focusing on sandwiching in particular, we provide novel arguments showing that there is a route for courts that adopt a moralized lens, focused on behavior that exploits privileged control over financial infrastructure, to find sandwiching impermissibly manipulative. We argue, further, that the legal hazards are even greater when it comes to sandwiching private transactions, which more clearly involves a heightened trust relationship, as well as disruptive schemes like oracle manipulation, wherein MEV is part of an independently manipulative strategy. Nonetheless, we argue, this alone does not mean a sweeping ban on these forms of MEV is necessarily a desirable policy. It remains unclear whether a strict ban on MEV sandwiching, for instance, would be prudent, given the unknowns about the net effects of MEV extraction and behavioral impact that a ban on MEV sandwiching would entail.
How to distinguish law from non-legal but systematic and ruleguided practices of legal officials? This issue features prominently in the debate on ‘positive originalism’ in US constitutional law, and in similar fundamental controversies in other legal orders. I take it as a question about content and constitution of ultimate rules of recognition. Legal philosophers have been too quick in dealing with this problem. I argue that there is more space to claim that non-officials have a constitutive relationship with the content of the law, thus potentially providing a standard to distinguish legal and non-legal practices of officials. However, to the extent officials play a constitutive role in the law, what matters is their genuine acceptance of ultimate rules of recognition. To show this, I develop the concept of ACCEPTANCE of a social rule by specifying the requirement of genuineness of acceptance and the role of mental dispositions associated with acceptance.
This paper tackles the question of methodological standards in public law scholarship, showing the perils of the current issues with access to relevant data and the promise of what can be achieved with better data and computational methods. It does so by focusing on the question of effectiveness of Cart challenges—the largest group of claims for judicial review in the High Court. Moreover, I discuss how the empirical question of effectiveness of judicial review is linked with the normative question of what counts as ‘success’. I show the perils of inattention to data limitations in the analyses of Cart claims by the Independent Review of Administrative Law and by the Government. I show the promise of better data and computational methods through my unprecedented empirical study of Upper Tribunal decisions that followed Cart judicial reviews. I find that the Government’s claim that Cart challenges are a disproportionate burden on resources lacks adequate empirical basis.
Markets built on public, permissionless blockchains like Ethereum are radically transparent. This creates opportunities and strategies that are rarely, if ever, seen in traditional markets. Among the most interesting but understudied of these is the use of sophisticated algorithms (“bots”) to automatically copy and front-run or otherwise exploit other users’ trades, as these are typically publicly viewable while they wait to be executed. In crypto markets like Ethereum, Generalized Profit-Seeker (GPS) bots can access publicly available pending orders (blockchain transactions), simulate them to determine if they will be profitable, and copy (or otherwise piggy-back on) those transactions deemed profitable according to the parameters of the bot. Sometimes, this benefits the sender of the copied order—the copier effectively facilitates, even subsidizes, its execution. Other times, the sender of the copied order is blocked from a profit opportunity because the copier manages to get there first, thus making it entirely unavailable or at least less profitable for anyone who comes second. To further complicate matters, such automated “strategy copying” may involve replicating or facilitating criminal or otherwise illicit transactions, such as attempted hacks of blockchain applications or platforms. This Article explores the legal implications of this type of radical transparency found in crypto markets and offers the first sustained legal analysis in the academic literature of the use of Generalized Profit-Seeking bots in crypto markets. This Article is part of a series on the legality of so-called Maximal Extractable Value (“MEV”) extraction techniques, which exploit the ability to order transactions in profitable ways including through the use of GPS bots which are the focus of this Article. In particular, we argue that, given the public and competitive nature of transaction ordering in crypto markets, the operation of GPS bots to copy profitable transactions submitted publicly is generally unlikely to be a legal violation in run-of-the-mill-cases. However, we highlight several exceptions to this default permissibility, for example where the GPS bot is operated by a validator, or when the bot copies criminal or illicit transactions. The Article provides a technical introduction of transaction ordering and execution on Ethereum to serve as a necessary resource for pressing legal and policy discussions. It then examines relevant U.S. laws governing market manipulation, insider trading, and front-running in securities and commodities markets, and analyzes what these entail for the use of GPS bots in crypto markets. Ultimately, the Article aims to offer guidance to regulators and policymakers, as well as courts and practitioners, on the legality of GPS bots and MEV extraction more generally under U.S. law, as well offering suggestions and questions for further research about how the use of crypto bots should be regulated going forward.
In cryptocurrency markets, maximal extractable value (“MEV”) is typically defined as “excess profit that a miner [validator] can extract by adjusting execution of user transactions.” MEV extraction has slowly been gaining broader recognition, e.g., from the Bank of International Settlements, the International Organization of Securities Commissions (“IOSCO”), and mainstream publications like Forbes. The Bank of International Settlements estimates that there has been between $550 and $650 million of total MEV volume since 2020. The aim of this paper is to provide an overview for policymakers regarding what we know today about MEV, but perhaps even more importantly, how much we do not know. I will offer general critical analysis of policy questions raised by MEV extraction on the Ethereum blockchain. The paper is intended both for those unfamiliar with MEV and those who are broadly familiar.I consider whether MEV extraction poses a problem that merits public-policy intervention. I argue that the mere fact that MEV extraction may adversely affect some market participants is not sufficient to answer that question. As in stock trading, which may likewise appear to be a zero-sum game with a “winner” and “loser” in each transaction, the nature and effects of MEV extraction have more dimensions that need to be considered.It is important to carefully consider the costs and benefits of regulatory responses to MEV extraction. Moreover, regulation and regulatory enforcement in the realm of public blockchains faces the problem of regulatory arbitrage. Operators may choose the most favorable jurisdictions, while retaining influence on markets in other jurisdictions. This provides a strong argument to prefer and support technical solutions that would apply globally over national or even international legal rules.
The aim of this chapter is twofold. First, it intends to show how constitutionally conforming interpretation (CCI) is understood in the Polish theory of legal interpretation and how it is applied by the Polish courts. To this end, the purposive and systemic roles of CCI are discussed, two types of CCI in Polish legal theory are distinguished, and the manner and extent to which CCI is applied in the Polish courts is examined. Second, given that Poland has been in a state of turbulent constitutional crisis in recent years, it is shown how CCI evolved into a tool for defending the rule of law against the unrelenting onslaught of the executive and legislative branches. This is partly achieved by analysing the altered perception of CCI within legal academia since the Law and Justice party came to power in 2015, and in particular, the tendency to use CCI as a tool to decentralise constitutional review and circumvent a subjugated and submissive Constitutional Tribunal. The chapter also attempts to determine whether this change in perception has influenced the decisions of the courts (ie whether practice has followed theory). This last aim is realized by a quantitative analysis of Polish case law that scans the linguistic corpus of court decisions and by measuring the frequency with which judges employ CCI.
The bulk of the legal literature that either builds on or criticizes Hayek focuses on Hayek’s work specifically devoted to law, in particular to the rule of law and to the common law. I aim to show that there is jurisprudentially valuable insight to be gained by reflecting on Hayek’s other work. I provide here a sketch of a synthesis of Hayek’s thought with the current standard framework in general theory (philosophy) of law, that of H. L. A. Hart. I begin by presenting the outlines of Hart’s model of the foundations of law with the ultimaterule ofrecognition at itscore. Then,Iexploretwo Hayekian themes which shed light on the foundations of law as understood by Hart. First, I consider the rule of recognition as an implicit (unconscious) social rule and a Hayekian spontaneous order. Second, I turn to Hayek’s discussion of ‘common opinion’ on which every official practice of law relies and argue that it should beseen ascomplimentary with Hart’s model. Finally, I provide an illustration of how Hayekian insights can improve a Hartian account of one of the topical debates in US constitutional law – that of the merits of positive originalism.
In this chapter, my focus is on an aspect of original constitutional founding moments (events that bring about a new constitutional order): the question of who made the constitution as law. Or, in other words, who was the legally authoritative agent (or author) in the making of a constitution? This question, for better or worse, plays a significant role in legal arguments about the legal content of some codified constitutions. I take no position on how significant, if at all, founding moments should be in constitutional law. I only offer a jurisprudential account of who, among the potentially many participants of a founding moment, counts as the legal authority who made the constitution (the constitution-maker). Lawyers across the globe routinely talk about what the 'founding fathers' or the 'framers' of their constitution (or a founding treaty) meant, expected, intended and so on. The point of this chapter is that some of the founding fathers talk is confused, because it refers to people who did not make the constitution. I dispel the confusion through analysis of what it means to be an agent behind making a constitution as law: what does it mean to be a constitution-maker?
My aim in this Paper is to analyze Professor Richard Kay’s notion of ‘constituent authority’ within H. L. A. Hart’s model of foundations of legal systems. I thus elucidate the relationship between constituent power, Kay’s constituent authority, and Hartian rules of recognition. I begin by distinguishing two understandings of constituent power: de facto and de jure. In general, constituent power is a power to bring about constitutional change that is not a legal power and is not constituted by (grounded in) any legal power. On the first view, constituent power is a factual capacity (e.g. a kind of social “power”) to bring about constitutional change. On the second view, constituent power is a normative (e.g. moral) power to bring about constitutional change. I stress that anyone aiming to apply a normative conception of constituent power needs to grapple with the difficult questions in moral and political philosophy entailed by the necessity of choosing a normative framework. I then introduce Professor Kay’s notion of “constituent authority,” which—unlike that of constituent power—can account for change of reasons that people have for acceptance of the authority of a constitution adopted at some point in the past. Elucidating Kay’s constituent authority, I argue that it is best understood as a kind of a normative social practice of acceptance of the authority of the makers of (1) an existing constitution or (2) a potential future constitution. The remaining key definitional question about both constituent powers and constituent authority is: what kind of constitutional change results from an exercise of either kind of a power? Can constituent power (authority) bring about any constitutional change, or is there some definitional restriction? Without giving a definite answer, I show various possible answers to this dilemma. I also argue that one potentially attractive possibility, tying the definition of constituent power or constituent authority to changes of rules of recognition, should be rejected. It should be rejected because it leads to a concept which is likely to be both under- and overinclusive. Finally, I discuss the possibility of lawful exercises of constituent power (and constituent authority). As I argue, it can even be that a constitutional change through a change of the rule of recognition is both, in a sense, a result of an exercise of a constituent power, and entirely lawful.
In R. (Buckinghamshire CC) v Secretary of State for Transport  UKSC 3;  1 W.L.R. 324 (HS2) the Supreme Court has provided a good reason to think that the idea of a hierarchy of statutes within the legal system of the United Kingdom is still alive, despite the fact that some commentators have already heralded its early demise (see e.g. Nicholas Bamforth, “Same-sex partnerships: some comparative constitutional lessons” (2007) E.H.R.L.R. 47 at 48). After the famous passage in Thoburn v Sunderland City Council  EWHC 195;  1 Q.B. 151 where Laws L.J. introduced the distinction between “constitutional” and “ordinary” statutes (at ), there indeed seemed to be some reticence among their Lordships to make use of this distinction and clarify its practical import. Among others, Lord Bingham of Cornhill in Robinson v Secretary of State for Northern Ireland  UKHL 32;  N.I. 390 at  and Lord Hope in H. v Lord Advocate  UKSC 24;  1 A.C. 413 at  have suggested a special role for constitutional statutes (respectively, being subject to a special mode of interpretation and being immune from implied repeal), but voices like those still remain isolated. In HS2 Lord Neuberger and Lord Mance appear to have decided to contribute to changing that situation by not only endorsing Laws L.J.’s distinction between two types of statutes (HS2 at ), but also by hinting that constitutional statutes and principles may be in some way entrenched against change by later constitutional statutes (at ).
In “Enduring Originalism,” Jeffrey Pojanowski and Kevin C. Walsh outline how originalism in constitutional interpretation can be grounded in modern natural law theory as developed by John Finnis. Their argument to that effect is powerful and constitutes a welcome addition both to natural law theory and to originalist theory. However, the authors chose to present their account as a superior alternative to, or modification of, “positive” (“original-law”) originalism of Stephen Sachs and William Baude. It is that aspect of the paper that I focus on in this short essay. Contrary to their strong claims in that direction, Professors Pojanowski and Walsh are far from establishing that positive originalism is deficient and that that their version of natural-law-based originalism offers a plausible alternative to positivist originalism. There is also a worry that, despite professing sympathy towards the “positive turn” in originalism, “Enduring Originalism” is at its core an account of what Professors Pojanowski and Walsh think the law should be, and not what the law is; precisely the kind of argument the positive turn militates against.
This article critically analyses the Supreme Court’s Miller judgment, taking it as an opportunity to reflect on the true place of EU law in UK law and on the right way to advance legal arguments on that point. It argues that the Miller majority did not provide an adequate answer to two strong arguments regarding interpretation of the European Communities Act 1972. Firstly, to the argument from the time-gap between enactment of the ECA and the moment Community law became directly effective in the UK. Secondly, to the argument from the purpose of s. 1(3) ECA, showing that the 1972 Act was enacted on the assumption of the orthodox dualist model.
In several recent cases the Supreme Court has endorsed the idea that there are some general limits to incorporation of European Union law in the United Kingdom. The general limits stem from the Court’s interpretation of the European Communities Act 1972, the statute that grounds domestic effect of EU law, construed both in the light of ordinary canons of interpretation and in the light of fundamental principles. This raises the question what are the legal consequences when an EU measure violates one of those limits. In this paper, I propose an answer from the perspective of what a domestic court ought to do. My aim is to develop the legal position emerging from Assange, HS2, Pham, and Miller. I argue that sometimes UK courts are under a duty not to apply EU law. However, the circumstances where this is the case are even more limited than the focus on the general limits of incorporation of EU law may suggest. In particular, fundamental principles of UK law may work to expand the scope of domestic effect of EU law. I want to stress that neither the cited cases, nor the present paper, take a position of hostility towards EU law. The following discussion makes it clear that both EU law and UK law have many devices to avoid conflict and those devices need to be exhausted before a court concludes that it is under a duty not to apply EU law.