There is no doubt that the rule of law is an important concept in political and constitutional thought. However, there is no consensus on what the ‘rule of law’ means. Is the rule of law content-free (thin) or content-rich (thick)? In this blog post, I provide an overview of some of the important academic writings on the thin and thick conceptions of the rule of law. I also analyse the arguments in support of the thick and thin versions of the rule of law. Ultimately, the philosophical debates about the rule of law provide a deeper dimension to a concept that is crucial to our constitutional understanding.
Advocates of the thin version of the rule of law are concerned with the ‘manner in which the law was promulgated’ [1]. The thin version is not concerned with the content of the law, but instead with the characteristics of the law. Raz’s account provides a good starting point to understanding the thin conception of the rule of law. According to Raz, the basic principle of the rule of law is that ‘the law must be capable of guiding the behaviour of its subjects’ [2]. Hence, the law should be – among other things – prospective, clear and relatively stable [3]. Furthermore, to ensure conformity to the rule of law, courts should be independent and accessible [4]. Two important points about Raz’s account should be borne in mind. Firstly, he does not deny that substantive values such as ‘democracy, justice, equality’ are important but emphasise that these values should be analysed separately from the rule of law [5]. The rule of law is ‘only one of the many virtues a legal system should possess’ [6]. This leads to the second point: the rule of law is a tool which, if used correctly, can facilitate the law in achieving its other purposes [7].
The attraction of the thin conception of the rule of law is its clear delineation between the formal and substantive aspects of the law. However, critics have argued that the thin conception itself encompasses substantive values. Allan argues that the thin conception of the rule of law ‘directs our attention to matters of individual right and human dignity’ [8]. Courts and public authorities must inevitably rely on underlying substantive principles to give practical effect to the procedural aspects of the rule of law [9]. For example, the doctrine of legitimate expectations has developed ‘to the point where a line between procedural and substantive fairness can no longer be clearly drawn’ [10]. I would argue that Allan’s argument does not immediately suggest that we should adopt the thick version of the rule of law. Just because the thin version may require the application of substantive values does not necessarily mean that the rule of law itself should encompass such values. However, the implication of Allan’s argument is important: if the boundary between the formal and substantive aspects of the law is artificial and ultimately untenable, one could argue that it may be better to adopt the thick conception of the rule of law instead.
The thick version of the rule of law prescribes requirements concerning the content of laws, in addition to any formal characteristics that the law should possess. Dworkin differentiates
between a ‘rule-book conception’ and ‘rights conception’ of the rule of law. He advocates for the rights conception: this is because ‘citizens have moral rights and duties with respect to one another, and political rights against the state as a whole’ [11]. Dworkin argues that these rights ought to be ‘recognised in positive law’ [12] and that individuals should be able to enforce these rights in the courts. In his illuminating book, Lord Bingham posits that the core principles of the rule of law include accessibility of the law and fair exercise of public power. Crucially, he argues that the rule of law should embrace the protection of human rights because a ‘state which savagely represses or persecutes sections of its people cannot […]be regarded as observing the rule of law’ [13].
We may find ourselves intuitively agreeing with the thick version of the rule of law – indeed, it is difficult to understand how a state that systematically oppresses its minorities could be seen as adhering to the rule of law. The concern, however, is that the thick version may foster too much uncertainty [14]. How do we determine which human rights ought to be included in the rule of law? If we conclude that only fundamental human rights should be included, it would beg the question of how to determine which human rights are fundamental in the first place. Determining which human rights to include in the rule of law will inevitably involve complex value judgements. Raz makes the point that to include substantive values in the rule of law would be akin to ‘[propounding] a complete social philosophy’ and would strip the rule of law of ‘any useful function’ [15]. Keeping substantive values out of the rule of law is thus an attempt to preserve the rule of law as an independent doctrine and ensure that it is agnostic across time and space.
It is clear that advocates of the thin and thick conceptions of the rule of law agree that substantive values are important in a legal system. Their key disagreement is whether these values should be analysed separately from the rule of law. The attraction of the formal approach is its clarity and its potential to be universally applicable; its drawback is that it may not be possible to draw a principled distinction between the formal and substantive aspects of the law in practice. On the other hand, the thick version is intuitively appealing but more difficult to apply universally. I would argue that the crux of the debate lies in how we view the role of the rule of law. Is the rule of law merely one virtue of a legal system (as Raz puts it) or is there a more fundamental role for the rule of law? Put in another way, is the rule of law a means by which the law achieves its purposes or an end in itself? This is perhaps what Allan meant what he stated that formal conception of the rule of law (and its attempt to separate justice and legality) assumes that ‘the law consists only in rules directed at the attainment of particular purposes’ and ‘overlooks the fundamental role of law as constituting a stable framework of rules’ [16]. As such, questions about the thick and thin versions of the rule of law cannot be divorced from our views about the nature and purpose of the law itself.
At its core, the rule of law is about ensuring that the government is ruled by law rather than by men (as the familiar trope goes). It is about preventing arbitrary exercise of power and respecting individual dignity. The philosophical debates regarding the thick and thin versions are important and engaging to consider. They remind us that the rule of law is not an uncontested concept; there are disagreements about what it means and what it should mean. Crucially, they also raise questions about how the rule of law should be applied in practice, and are tangled up with questions about the purpose and nature of the law itself.
Notes
[1] Paul Craig, ‘Formal and substantive conceptions of the rule of law: an analytical framework’ [1997] Public Law 467.
[2] Joseph Raz, The Authority of Law: Essays on Law and Morality (Oxford: OUP 1979) 214.
[3] ibid 214-217.
[4] id.
[5] ibid 211.
[6] ibid 219.
[7] ibid 229.
[8] Trevor RS Allan, Law, Liberty and Justice: The Legal Foundations of British Constitutionalism (Oxford: Clarendon Press 1994) 39.
[9] ibid 28-29.
[10] ibid 29.
[11] Ronald Dworkin, Matter of Principle (Harvard University Press 1985) 11.
[12] id.
[13] Lord Bingham, The Rule of Law (Allen Lane 2010) 67.