The goal of this study is to assess the soundness of the thesis that the Brazilian system of diffuse judicial review has undergone a “constitutional mutation”, specifically regarding the Federal Senate’s constitutional prerogative to suspend the enforcement of any law or normative act that has been declared unconstitutional by the Supreme Federal Court by means of concrete review. This “constitutional mutation” argument has been employed by Justice Gilmar Ferreira Mendes in the judgment of the Reclamação 4.335-5/AC by the Brazilian Supreme Federal Court. To assess the consistency of this thesis, this paper does an empirical analysis of the role of the Brazilian Senate in using the powers conferred to it by article 52, X, of the 1988 Constitution. This argument also supports the idea that any instances of constitutional reasoning based on “constitutional mutation” cannot be grounded only on doctrinal and jurisprudential inputs and require empirical analysis in order to be justified.
Diffuse judicial review; Constitutional mutation; Supreme Federal Court; Federal Senate; Separation of powers