Significant changes to the Constitution come about through the interpretation of the Constitutional Courts and Tribunals and not through the formal means provided for this. It is in this context that the phenomenon of constitutional mutation is inserted. Commonly referred to as a change in the sense, meaning and scope of the rule despite the inalterability of its text, this concept fails to satisfactorily explain the wide variety of cases listed by the doctrine as hypotheses of constitutional mutation. This dissatisfaction is due to the factual and legal complexity involved in the phenomenon of mutation. Not every interpretative change by the courts corresponds to the complexity of a mutation. We therefore analyze the necessary differentiation between interpretation and the phenomenon of constitutional mutation in the light of the Principle of Separation of Powers and its representative role in democratic dynamics.