This research analyzed the extent and meaning of expressions adopted by ministers of the Federal Supreme Court, such as notable factual or legal changes or alterations, used to support informal constitutional mutations of provisions of the original wording of the Constitution of 88, and whether this would provide a basis appropriate and specific, observing the principles of legal certainty, protection of trust and equality, required by the Code of Civil Procedure. The methodology applied was empirical research through the study of four cases judged by the Full Court, from 10.05.1988 to 11.24.2022, when ten judicial constitutional mutations detected in them were analyzed. And in the end, the hypothesis of unfounded, adequate and specific judicial exercise was confirmed, without observing the aforementioned procedural principles. And as contributions to the formation of a Brazilian theory of judicial constitutional mutation, a new concept of the phenomenon was presented, a proposal for its systematization for use by the Plenum of the STF, and a list of certain circumstances that proved to be irrelevant to its occurrence.