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Leslie Green

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Professor of the Philosophy of Law*

Les Green is the Professor of the Philosophy of Law and Fellow of Balliol College.  He also holds a part-time appointment as Professor of Law and Distinguished University Fellow at Queen's University in Canada.  After beginning his teaching career as a fellow of Lincoln College, Oxford, he moved to Osgoode Hall Law School in Toronto.  He has also been a visiting professor at many other law faculties, including Berkeley, NYU, Chicago and, for some years, at the University of Texas at Austin.  Professor Green writes and teaches in the areas of jurisprudence, constitutional theory, and moral and political philosophy.  He serves on the board of several journals and is co-editor of the annual Oxford Studies in Philosophy of Law and of the book series Oxford Legal Philosophy.


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Journal Articles


L Green, 'Should Law Improve Morality?' (2013) 7 Criminal Law and Philosophy 473 [...]

DOI: 10.1007/s11572-013-9248-3

Lawyers and philosophers have long debated whether law should enforce social morality. This paper explores whether law should improve social morality. It explains how this might be possible, and what sort of obstacles, factual and moral, there are to doing so. It concludes with an example: our law should attempt to improve our social morality of sexual conduct.

ISBN: 1871-9791


L Green, 'Jurisprudence for Foxes' (2012) 3 Transnational Legal Theory 150 [...]

DOI: 10.5235/TLT.3.2.150

This paper contests Brian Simpson's claim that HLA Hart's book, The Concept of Law, is that of a 'hedgehog,' that is, a procrustean and monistic thinker. It is not. Hart's work is pluralist both in its explanatory concepts and in its evaluative background. It is, of course, a philosophical book; but that is not enough to make it monistic. Some conjectures are offered as to why Simpson so badly misunderstood Hart, and as to why analytic legal philosophy is misunderstood, or distrusted, more generally.


L Green, 'Sex-Neutral Marriage' (2011) 64 Current Legal Problems 1 [...]

DOI: 10.1093/clp/cur014

A different-sex marriage need not be a marriage between heterosexuals, and a same-sex marriage need not be a marriage between homosexuals. This shows how little the law of marriage cares about the sexuality of parties to a marriage; it does not show that sex-restricted marriage laws do not discriminate on grounds of sexual orientation. They do. Neither does the law care much about sex, let alone possibly procreative sex, within marriage. The voidability of a different-sex marriage on grounds of non-consummation does not show otherwise. The formation of a valid marriage was always a matter of consent, not coitus. But what should happen to the doctrine of non-consummation in a sex-neutral marriage regime? It is an anachronism that should be abolished.

ISBN: 0070-1998


L Green, 'Two Worries about Respect for Persons' (2010) 120 Ethics 212


L Green, 'Filosofia del derecho general' (2009) 3 Problema: anuario de filosofia y teoria del derecho 289 [...]

Spanish translation of 'General Jurisprudence: a 25th Anniversary Essay'. Translated by Enrique Rodriguez Trujano & Pedro A. Villarreal Lizarraga.


L Green, 'Positivism and the Inseparability of Law and Morals' (2008) 83 New York University Law Review 1035 [...]

This article seeks to clarify and assess HLA Hart's famous claim that legal positivism somehow involves a “separation of law and morals.” The paper contends that Hart's “separability thesis” should not be confused with the “social thesis,” with the “sources thesis,” or with a methodological thesis about jurisprudence. In contrast to all of these, Hart's separability thesis denies the existence of any necessary (conceptual) connections between law and morality. But that thesis is false: there are many necessary connections between law and morality, some of them conceptually significant. Among them is an important negative connection: law is of its nature morally fallible and morally risky. Lon Fuller emphasized what he called the “internal morality of law,” the “morality that makes law possible”. Hart’s most important message is that there is also an immorality that law makes possible. Law's nature is seen not only in its internal virtues, in legality, but also in its internal vices, in legalism.

ISBN: 0028-7881


L Green, 'The Duty to Govern' (2007) 13 Legal Theory 165


L Green, 'Men in the Place of Women, from Butler to Little Sisters' (2006) 44 Osgoode Hall Law Journal 1


L Green, 'General Jurisprudence: a 25th Anniversary Essay' (2005) 25(4) Oxford Journal of Legal Studies 565

L Green, 'Three Themes from Raz' (2005) 25 Oxford Journal of Legal Studies 503


L Green, 'Civil Disobedience and Academic Freedom' (2003) 41 Osgoode Hall Law Journal 380

L Green, 'Strategy and Fundamental Legal Rules' (2003) American Philosophical Association Newsletter on Law and Philosophy 69


L Green, 'Pornographies' (2000) 8 Journal of Political Philosophy 27


L Green, 'Positivism and Conventionalism' (1999) 12 Canadian Journal of Law and Jurisprudence 35


L Green, 'Rights of Exit' (1998) 4 Legal Theory 165

L Green, 'The Functions of Law' (1998) 12 Cogito 117


L Green, 'The Concept of Law Revisited' (1997) 94 Michigan Law Review 1687


L Green, 'Les minorites internes et leurs droits' (1994) 4 Lekton 81


L Green and Denise Reaume, 'Bilingualism, Territorialism, and Linguistic Justice' (1991) 1 Network: Newsletter on the Constitution

L Green, 'Freedom of Expression and Choice of Language' (1991) 13 Law and Policy 215

L Green, 'Two Views of Collective Rights' (1991) Canadian Journal of Law and Jurisprudence 315


L Green and D Reaume, 'Second Class Rights? Principle and Compromise in the Charter' (1990) 13 Dalhousie Law Journal 564


L Green and D Reaume, 'Education and Linguistic Security in the Charter' (1989) 34 McGill Law Journal 777

L Green, 'Law, Legitimacy and Consent' (1989) Southern California Law Review 795


L Green, 'Kant's Liberalism: A Reply to Rolf George' (1988) 27 Dialogue 207

L Green, 'Un-American Liberalism: Raz's Morality of Freedom' (1988) 38 University of Toronto Law Journal 317


L Green, 'Are Language Rights Fundamental?' (1987) 25 Osgoode Hall Law Journal 639

L Green, 'The Political Content of Legal Theory' (1987) 17 Philosophy of the Social Sciences 1


L Green, 'Law's Rule' (1986) 24 Osgoode Hall Law Journal 1023


L Green, 'Authority and Convention' (1985) 35 Philosophical Quarterly 329

L Green, 'Legality and Community' (1985) 5 Oxford Journal of Legal Studies

L Green, 'Support for the System' (1985) 15 British Journal of Political Science 127

L Green, 'What is a Dictator?' (1985) 45 Analysis 125


L Green, 'The Techniques and Limits of Law' (1984) 9 Queen's Law Journal 328


L Green, 'Dictators and Democracies' (1983) 43 Analysis 58

L Green, 'Law, Co-ordination and the Common Good' (1983) 3 Oxford Journal of Legal Studies 299



L Green, The Authority of the State (Chinese Edition) (China University of Political Science and Law Press 2013) [...]

Abstract: This is a Chinese translation, by Singgui Mao, of the corrected 1990 edition of The Authority of the State (Oxford University Press).

ISBN: 7562046468


L Green, The Authority of the State (Clarendon Press 1990)



L Green, 'Pornographies' in Nicholas Bamforth (ed), Sexual Orientation and Human Rights (Ashgate, International Library of Essays on Rights 2014) [...]

Reprinting 'Pornographies', first published 8 Journal of Political Philosophy, (2000), 27-52.

ISBN: 978-1-4094-3040-7

L Green, 'Reconsiderando El Concepto de Derecho' in S F Rubio (ed), Hart en la Teoria del Derecho Contemporanea (Ediciones Universidad Diego Portales 2014) [...]

Spanish translation by Erensto Riffo of 'The Concept of Law Revisted', first published in 94 Michigan Law Review 1687 (1996)


L Green, 'Sex-Neutral Marriage' in J Feinberg, J Coleman, and C Kutz (eds), Philosophy of Law (Cengage Learning 2013) (forthcoming)


L Green, 'Introduction to the Concept of Law' in The Concept of Law, 3rd Edition (Oxford University Press 2012)

L Green, 'Obscenity without Borders' in F Tanguay-Renaud and J Stribopolous (eds), Rethinking Criminal Law Theory ( 2012)

L Green, 'The Nature of Limited Government ' in R George and J Keown (eds), Reason, Morality, and the Law: The Jurisprudence of John Finnis (Oxford Univiersity Press 2012)


L Green, 'El Positivismo y la inseparabilidad del derecho y la moral' in M.E. Orellana Benada (ed), Causas Perdidas: ensayos de filosofia juridica, politica y moral (Catalonia 2010)

L Green, 'General Jurisprudence' in Michael Giudice, Wil Waluchow, and Maksymilian del Mar (eds), The Methodology of Legal Theory, vol. I (Ashgate 2010)

L Green, 'Law as a Means' in P Cane (ed), The Hart-Fuller Debate in the Twenty-First Century (Hart Publishing, Oxford 2010)


L Green, 'On Being Tolerated' in M Kramer, C Grant, B Colborn, A Hatzistavrou (eds), The Legacy of HLA Hart: Legal, Political, and Moral Philosophy (Oxford University Press 2008) [...]

Why is it that toleration can be uncomfortable for the tolerated? And how should tolerators respond to that discomfort? This paper argues that properly directed toleration can be deficient in its scope, grounds or spirit. That explains some of the discomfort in being tolerated. Beyond this, the occasions for toleration¿the existence of a power to prevent and of an adverse judgment¿can also make toleration sting. The paper then explores and rejects two familiar suggestions about how one should respond to this discomfort: with acceptance or recognition of the tolerated. It is proposed instead that toleration should be supplemented by understanding. The nature and importance of this attitude are assessed.

ISBN: 978-0-19-954289-5


L Green, 'Sexuality, Authenticity and Modernity' in J Feinberg & J Coleman (eds), Philosophy of Law, 8th Edition (Cengage Publishing 2007)

L Green, 'Who Believes in Political Obligation?' in Shinggui Mao trans (ed), Political Obligation: Justifying and Refuting (Nanjing: Jiangsu People's Publishing House 2007) [...]

Abstract: (Paper in Chinese): It is often supposed that most people believe they have a duty to obey the law. Examining empirical work by Tom Tyler and others, I show that the evidence offered for this proposition does not in fact support it. Existing surveys are all consistent with only much weaker popular attitudes to law. Suggestions are made about an appropriate test for this belief.


L Green, 'Associative Obligations and the State' in Justine Burley (ed), Dworkin and his Critics (Blackwell 2004)


L Green, 'Law and Obligations' in J. Coleman and S. Shapiro (eds), The Oxford Handbook of Jurisprudence and Philosophy of Law (OUP 2002)


L Green, 'Pluralism, Social Conflict, and Tolerance' in A Soeteman (ed), Pluralism and Law (Springer 2001)


L Green, 'Sexuality, Authenticity, and Morality' in J Feniberg and J Coleman (eds), Philosophy of Law, 5th Ed. (Wadsworth 1999)

L Green, 'Who Believes in Political Obligation?' in W Edmundson (ed), The Duty to Obey the Law (Rowman and Littlefield 1999)


L Green, 'Authority' in E Craig (ed), Routledge Encyclopedia of Philosophy (Routledge 1998)

L Green, 'Pornographizing, Subordinating, and Silencing' in R Post (ed), Censorship and Silencing: Practices of Cultural Regulation (Getty Research Institute 1998)

L Green, 'Power' in E Craig (ed), Routledge Encyclopedia of Philosophy (Routledge 1998)


L Green, 'Freedom of Expression and Choice of Language' in E Soifer (ed), Ethical Issues: Perspectives for Canadians (Broadview Press 1997)


L Green, 'Who Believes in Political Obligation?' in J Narveson & JT Sanders (eds), For and Against the State (Rowman and Littlefied 1996)


L Green, 'Internal Minorities and their Rights' in W Kymlicka (ed), Rights of Cultural Minorities (Oxford University Press 1995)


L Green, 'Freedom of Expression and Choice of Language' in WJ Waluchow (ed), Free Expression: Essays in Law and Philosophy (Oxford University Press 1994)

L Green, 'Internal Minorities and their Rights' in J Baker (ed), Group Rights (University of Toronto Press 1994)


L Green, 'Concepts of Equity in Taxation' in A Maslove (ed), Fairness in Taxation: Exploring the Principles (University of Toronto Press 1993)


L Green, 'Consent and Community' in J Raz (ed), Authority (Blackwell 1991)


L Green, 'Consent and Community' in P Harris (ed), On Political Obligation (Routledge 1990)

L Green, 'Legal Ethics: Sociology and Morality' in D MacNiven (ed), Moral Expertise ( 1990)


L Green, 'Associative Obligations and the State' in L Green and A Hutchinson (eds), Law and the Community: The End of Invidualism? (Carswell 1989)

L Green, 'Loyalty, Security, and Democracy' in P Hanks and JD McCamus (eds), National Security: Surveillance and Accountability in a Democratic Society (Yvon Blais 1989)

Edited books


L Duarte d'Almeida, J Gardner and L Green (eds), Kelsen Revisited: New Essays on the Pure Theory of Law (Hart Publishing 2013) [...]

Forty years after his death, Hans Kelsen (1881-1973) remains one of the most discussed and influential legal philosophers of our time. This collection of new essays takes Kelsen's Pure Theory of Law as a stimulus, aiming to move forward the debate on several central issues in contemporary jurisprudence. The essays in Part I address legal validity, the normativity of law, and Kelsen's famous but puzzling idea of a legal system's 'basic norm'. Part II engages with the difficult issues raised by the social realities of law and the actual practices of legal officials. Part III focuses on conceptual features of legal systems and the logical structure of legal norms. All the essays were written for this volume by internationally renowned scholars from seven countries. Also included, in English translation, is an important polemical essay by Kelsen himself.

ISBN: 9781849464567

L Green and B Leiter (eds), Oxford Studies in Philosophy of Law (Oxford University Press 2013)


L Green and B Leiter (eds), Oxford Studies in Philosophy of Law (Oxford University Press 2011)


L Green and Allan C. Hutchinson (eds), Law and the Community: The End of Individualism? (Carswell 1989)

Internet Publications


L Green, 'The Forces of Law: Duty, Coercion and Power' (2015) Oxford Legal Studies Research Paper [...]

This paper addresses the question of the relationship between law and coercive force. It defends, against Frederick Schauer’s claims in his book, The Force of Law, the following propositions: (a) the force of law consists in three things, not one: the imposition of duties, the use of coercion, and the exercise of social power. These are different and distinct. (b) Even if coercion is not part of the concept of law, coercion is connected to law in a variety of ways. These are amply recognized in contemporary jurisprudence. (c) We cannot determine how important coercion is to the efficacy of law until we know what counts as coercive force. This question is not a matter for empirical generalization or bare stipulation. It requires an explanation of the concept of coercion.


L Green, 'Law and the Role ofa Judge' (2014) Oxford Legal Studies Research Paper [...]

This paper argues that role of a judge consists of obligations to apply the law, obligations to improve the law, and obligations to protect the law. It defends this view against a competing suggestion by Michael Moore, who claims that, when acting judicially, judges are always obligated to apply the law, and the law alone. I argue that this depends on an incorrect view of the relationship between social roles and moral obligations, and an unacceptably capacious view of what the law is. I conclude by asking whether there nonetheless room to make a ‘conceptual choice’ to see law as Moore thinks of it, or a reason to reform the concept of law along such lines. I reject both ideas. There are fewer ‘conceptual choices’ in jurisprudence than some people think.


L Green, 'Should Law Improve Morality?' (2013) 73/2013 Oxford Legal Research Paper Series [...]

Legal theorists have long debated whether law should enforce social morality. This paper explores a different problem: should law (try to) improve social morality? I argue that it should. First, against conceptual and empirical doubts, I argue that it is possible for law to improve morality. Second, against certain moral objections, I argue that it is often proper for law to try to improve it. Third, I offer an example: law should try to improve our social morality of sex, by trying to re-shape what we regard as valid consent to sexual activity. Along the way, the ideas of H. L. A. Hart and Patrick Devlin are examined, as are the empirical and policy claims of Paul Robinson and his collaborators. A revised version of the paper is to appear in Criminal Law and Philosophy.

L Green, 'The Morality in Law' (2013) 12/2013 Oxford Legal Studies Research Paper [...]

This paper tests the claim, made by H.L.A. Hart, that nothing is a legal system that fails to include certain obligations familiar in morality . This ‘minimum content’ thesis was rejected by Hans Kelsen, among others. Hart’s arguments for the minimum content thesis are unsound; but the thesis is correct and a different defense of it is offered. Two general worries about the thesis are then addressed. Brian Leiter argues that, since law is an artefact, it has no essential properties at all and, a fortiori, no essential content. This is shown to involve several errors. Others argue that Hart’s view about the relation between law and morality is not a theoretical thesis at all: it is the practical thesis that we should try to improve law by improving the concept of law. It is shown that this is not a possible interpretation of any of Hart’s arguments: ‘normative positivism’ has no Hartian foundations.


L Green, 'Jurisprudence for Foxes' (2012) Oxford Legal Studies Research Paper [...]

This paper contests Brian Simpson's claim that HLA Hart's book, The Concept of Law, is that of a 'hedgehog,' that is, a monistic thinker. It is not. Hart's work is pluralist both in its explanatory concepts and in its evaluative background. Some conjectures are offered as to why Simpson so misunderstood Hart, and as to why analytic legal philosophy is misunderstood, or distrusted, more generally.

L Green, 'The Nature of Limited Government' (2012) Oxford Legal Studies Research Paper [...]

This paper explores moral limits on state action: their sources, character, and stringency. It explains what is special about the liberal tradition: there must be a protected sphere of action, and governments must respect legality. It argues, against Patrick Devlin, that the possible absence of absolute moral reasons against intrusion in a sphere is consistent with justified absolute positive limits on government intrusion. It argues, against John Finnis, that the fact that some associations (e.g. churches or marriages or universities) have intrinsically valuable ‘common goods’ does not entitle them to immunity from government regulation. It concludes by suggesting why certain ‘natural law’ moralities have been considered unreasonably intrusive, for they neglect the significance of moral fallibility for limited government.

L Green, 'What is Freedom For?' (2012) Oxford Legal Studies Research Paper [...]

Two conceptions of the value of political freedom are popular. According to one, freedom serves autonomy, creating one’s own path through life. According to the other, freedom serves authenticity, keeping faith with an identity one did not choose. This paper bridges the gap between these views in several ways. It shows that autonomy embraces some of the unchosen aspects of life that authenticity stresses, and that authenticity is consistent with scope for choice within an unchosen identity. It is also shows that both views share a stake in a neglected value, self-knowledge. Partisans of authenticity cannot keep faith with their identity if they do not know what it truly is. Partisans of autonomy cannot choose a path in life without knowing what the options are for them, and these options can be affected instrumentally and constitutively by their identity, which they therefore have a stake in knowing. Of course, there can be more than one sound argument in favor of freedom. But contrary to what many suppose, autonomy and authenticity are complementary, not competing, in making that case. The differences between them are matters of nuance and degree.


L Green, 'The Germ of Justice' (2010) Oxford Legal Research Papers [...]

This paper addresses the perennial question of the relationship between law and justice. HLA Hart argued that ‘we have, in the bare notion of applying a general rule of law, the germ, at least, of justice.’ If true, this establishes a necessary connection between law and morality. That is no objection, for the so-called ‘separability thesis’ is anyway false. But the ‘germ-of-justice’ thesis is also false. Justice is a matter of the correct allocation of benefits and burdens among people. Contrary to what Hart and others think, there is not necessarily any injustice in failing to apply a valid legal rule, not even an ‘administrative’ injustice. It is readily conceded that ‘formal justice’ is not enough in law, that we also need ‘substantive justice’. This too is a mistake. Formal justice is not insufficient; it is incoherent--all justice is substantive. Might constant rule-application do justice by promoting impartiality? Not necessarily. It depends on the content of the rules and on the nature of the of the adjudicator’s prejudices. There is nonetheless a weak connection between law and justice. Every legal system has courts whose job it is to aim at justice: they must decide not only whether plaintiff deserves a remedy, or whether the prosecution is entitled to a conviction, but also whether these should be ordered in the face of a claim to the contrary. Courts have an allocative job to do. This does not show that they must achieve justice, or even a minimum of justice. Nor does it show that justice is the first virtue of legal institutions. The connection between law and justice is real, but modest. Justice is a necessary aim of a necessary legal institution.


L Green, 'Law and the Causes of Judicial Decisions' (2009) 14/2009 Oxford Legal Research Paper Series 1 [...]

This paper tests Brian Leiter's claim that the American legal realists were proto-naturalists in legal philosophy and were thus immune to objections based on claims that they offered defective analyses of legal concepts. It disputes Leiter's account of the core claim of realist thought, and reaffirms the view that some of them were indeed engaged in, or presupposed, conceptual work of a kind familiar to analytic jurisprudence. It explains how those who did not intend to offer conceptual analyses nonetheless made conceptual errors. It offers a fresh account of the basis of the realists scepticism, here deploying the idea of 'permissive sources' of law. The paper concludes with reflections on the preconditions and prospects for 'naturalizing' jurisprudence, suggesting that Hans Kelsen was correct to think that such efforts will either fail, or will simply change the subject.


L Green, 'Legal Obligation and Authority' (2003) Stanford Encyclopedia of Philosophy [...]

Whatever else they do, all legal systems recognize, create, vary and enforce obligations. This is no accident: obligations are central to the social role of law and explaining them is necessary to an understanding of law's authority and, therefore, its nature. Not only are there obligations in the law, there are also obligations to the law. Historically, most philosophers agreed that these include a moral obligation to obey, or what is usually called “political obligation.” Voluntarists maintained that this requires something like a voluntary subjection to law's rule, for example, through consent. Non-voluntarists denied this, insisting that the value of a just and effective legal system is itself sufficient to validate law's claims. Both lines of argument have recently come under intense scrutiny, and some philosophers now deny that law is entitled to all the authority it claims for itself, even when the legal system is legitimate and reasonably just. On this view there are legal obligations that some of law's subjects have no moral obligation to perform.

L Green, 'Legal Positivism' (2003) Stanford Encyclopedia of Philosophy [...]

Legal positivism is the thesis that the existence and content of law depends on social facts and not on its merits. The English jurist John Austin (1790-1859) formulated it thus: “The existence of law is one thing; its merit and demerit another. Whether it be or be not is one enquiry; whether it be or be not conformable to an assumed standard, is a different enquiry.” (1832, p. 157) The positivist thesis does not say that law's merits are unintelligible, unimportant, or peripheral to the philosophy of law. It says that they do not determine whether laws or legal systems exist. Whether a society has a legal system depends on the presence of certain structures of governance, not on the extent to which it satisfies ideals of justice, democracy, or the rule of law. What laws are in force in that system depends on what social standards its officials recognize as authoritative; for example, legislative enactments, judicial decisions, or social customs. The fact that a policy would be just, wise, efficient, or prudent is never sufficient reason for thinking that it is actually the law, and the fact that it is unjust, unwise, inefficient or imprudent is never sufficient reason for doubting it. According to positivism, law is a matter of what has been posited (ordered, decided, practiced, tolerated, etc.); as we might say in a more modern idiom, positivism is the view that law is a social construction. Austin thought the thesis “simple and glaring.” While it is probably the dominant view among analytically inclined philosophers of law, it is also the subject of competing interpretations together with persistent criticisms and misunderstandings.


Teaching: Philosophy of Law; Human Rights Law

Research: Legal Philosophy, Jurisprudence, Constitutional Theory, Human Rights

Other details

Correspondence address:

Balliol College
Oxford OX1 3BJ

other affiliation(s):

Oxford Human Rights Hub

Link to personal web site

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