The powers within a state, of both the executive and the judiciary, must be exercised subject to the principle of equality or equal treatment. This is almost trivial. The problem is that, whilst the principle may be stated simply, imposing such an equality obligation on the legislative body is far from trivial, and must rank as a major achievement of democratic constitutionalism: only a fully functioning mechanism for constitutional review genuinely provides equality, in relation to any given constitution. The principle of constitutional equality is embodied, in this sense, by the general fundamental right to equal implementation of the (constitutional) law. The aim here is to demonstrate how the principle of equality has emerged and evolved in relation to Estonian constitutional law, by conducting a structural analysis of the doctrine, together with an analysis of the main questions posed during its implementation. This is achieved through systematic analysis and criticism of relevant case-law