How did the French Declaration of the Rights of Man and of the Citizen connect rights with separation of powers?

The French Declaration of the Rights of Man and of the Citizen connects the protection of individual rights directly to the separation of powers as a fundamental requirement for a legitimate constitution.

Article 16 of the document explicitly states: "Any society in which the guarantee of rights is not assured, nor the separation of powers determined, has no constitution." This principle reflects the belief that rights cannot be effectively safeguarded unless governmental functions—legislative, executive, and judicial—are divided among distinct agencies. By separating these powers, the framers aimed to prevent any single branch from acting as a "judge in its own cause," thereby ensuring that those who create laws are subject to them and that the judiciary and executive act impartially.1

However, while the Declaration affirmed the necessity of this separation, it did not establish a mechanism like a supreme court to enforce it. Consequently, the legislature remained the ultimate judge of its own actions, leaving the practical guarantee of rights dependent on the legislative process rather than an autonomous judicial check.2