Dicey's first pillar is the absolute supremacy of regular law over arbitrary power, meaning no one can be punished except for a distinct breach of law. The second is equality before the law—every official, from the Prime Minister to a tax collector, is subject to the same ordinary courts and laws. The third is that individual rights derive not from abstract declarations but from judicial remedies in specific cases. These principles constrain Parliament not by legally invalidating statutes (which sovereignty prevents) but by establishing the substantive moral and procedural framework that Parliament must implicitly respect to preserve the rule of law itself.

Legal sovereignty resides exclusively in the Queen-in-Parliament, which has the recognized legal power to make or unmake any law whatever—a power that courts must always recognize. Political sovereignty, by contrast, resides in the electorate, who ultimately determine which laws are politically feasible through elections and public opinion. Dicey deployed this distinction to explain why Parliament legally could do anything (e.g., abolish the House of Lords) but politically must heed the electorate, bridging the gap between formal legal authority and actual democratic accountability.

Dicey's doctrine views EU law's supremacy as a direct violation of parliamentary sovereignty, because it prevents Parliament from legislating contrary to EU directives—a tension that underpinned the UK's Brexit debate. Similarly, the Human Rights Act 1998, which requires courts to interpret laws compatibly with Convention rights, partially undermines Dicey's literal sovereignty by empowering judges to issue declarations of incompatibility. Modern courts have responded by asserting common law rights independent of statute, proving that Dicey's framework remains the baseline against which every constitutional innovation is measured.

Conventions are political rules—such as the Prime Minister being a member of the House of Commons or the monarch assenting to all legislation—that are not enforceable in courts but are binding in practice. Dicey argued they are essential because they bridge the gap between formal legal powers (e.g., the monarch's prerogative to refuse assent) and actual political behavior. Their non-justiciability means courts cannot adjudicate their violation; enforcement is purely political, and breach leads to a constitutional crisis rather than a legal remedy—a distinction that remains fundamental to Westminster-style governance.

Dicey's model overestimated parliamentary control and underestimated the growth of delegated legislation (statutory instruments) that grants executives quasi-legislative power with minimal parliamentary scrutiny—undermining his ideal of legislative supremacy. He also failed to anticipate the rise of administrative tribunals operating outside ordinary courts, which his rule-of-law framework struggled to accommodate. Yet his core distinction between law and convention, his insistence that officials be subject to ordinary courts, and his articulation of legal sovereignty as the ultimate rule of recognition remain the indispensable starting point for any constitutional analysis.

Dicey's model categorically rejects judicial review of legislation for substantive content, because Parliament is sovereign and its enactments cannot be struck down by courts. In the American system, the Constitution is a supreme written document above the legislature, and courts possess explicit constitutional review power to invalidate laws violating it. Dicey saw the British model as more democratic because it trusts the elected legislature, while the American model trusts unelected judges as guardians of a foundational text—a fundamental divergence that shapes each system's approach to rights protection and federalism.

Dicey argued that the English constitution is not a single, written, supreme document enacted by a constituent assembly, but rather the ordinary law of the land as interpreted by courts and supplemented by conventions. Because Parliament is sovereign, there is no higher legal rule that cannot be altered by ordinary statute. For Dicey, this made the English constitution more flexible, historically grounded, and rooted in legal remedies rather than abstract declarations—a distinctiveness he considered a strength, though critics see it as a vulnerability to executive overreach.