Rule of Law - A Normative Principle of Democracy

The rule of law is a key normative democratic principle which acts as the foundation for other principles, however they might be characterised or named. The starting point adopted is that the rule of law is “the base upon which every other dimension of democratic quality rests” (Diamond and Morlino, 2004, p. 5). This positions the concept of law as not just a procedure engaged in by, or applied to, a population, but morally constitutive of democracy.

The rule of law contains inherent tensions that complicate its role as a normative benchmark. Diamond and Morlino note that weak law disproportionately harms the poor and marginalised, undermining participation, equality and accountability (p. 5-6). This does not detract from the rule of law being a normative principle. It does expose a weakness in applied democracy itself.

Adamidis’ discussion of populism (Adamidis, 2024) highlights tensions between thick and thin definitions of the rule of law (p. 6) with populism at one end and liberal democracy at the other. This reinforces the idea that rule of law is a required principle. It frames the rule of law as having difficulties in defining what constitutes a government with weak and strong democracy.

That democratic governments may seek to constrain the legal framework which enabled them to gain power provides a strong indication that rule of law is a core measure. Building on Adamidis, when tracing the principle through, it is useful to position rule of law as an ethical concept at the thin end, requiring little in the way of what the rule of law might contain, except that there is a mechanism which seeks to provide a structure for governance. Contrast this with the thick end, where morality emerges from the rule of law seeking to ensure that aspects of fairness for all, for example, are contained within statutes.

When assessing the quality of democracy, the rule of law is best approached first as a baseline normative principle, before specifying what content should be included. Once established as a normative starting point it is analytically useful to distinguish between thin and thick versions of the rule of law, allowing different democratic forms to be situated along a spectrum of legal constraint (Adamidis, 2024, p. 6). This distinction is analytically useful in that it provides a structured way to compare how different democratic systems exhibit the rule of law, without challenging its status as a foundational normative principle.

The literature provides a number of versions of rule of law scales, starting with empty normative baselines. Møller and Skaaning explore thin and thick versions of the rule of law, mapped neatly onto a matrix (2012, p. 8 and 11), with thin legality providing only the ethical minimum of rule‑governed authority and thick legality embedding the moral commitments, or constraints, of rights and justice. Krygier’s lecture reinforces this by arguing that the rule of law’s core purpose may be characterised as a constraint on arbitrary abuse of power, generating tensions between procedural form and deeper moral aspiration (2011, p. 12), underscoring why it must remain the starting point for evaluating democratic quality.