This study intends to analyse the constitutionally established limits to the separation of powers at the federal level, especially with regard to the competencies of Brazilian s Supreme Court (BSC). It is asked whether there is, currently, some equivalence between the tasks of the moderating power during the Brazilian Empire and some of the functions constitutionally assigned to the constituted powers. It is believed that there is an opening to the moderating tendency in the BSC competencies, which is revealed by the court s jurisprudence. Methodologically, the theoretical references here applied consist in a dynamic perspective that distinguishes democracy from monarchy and aristocracy thought a difference of directions. In a democracy the desire to govern is open to fulfilment meanwhile in the other forms of government this desire remains captive. In fact, this methodological approach proposes the reconstruction of a system of analytical concepts based on contemporary constitutional theory in order to understand the role play by the BSC. The Brazilian judicial review system is a unique creation, from which emerge a moderating tendency with autocratic trends, highlighted by the self-restraint duty and the court s competent speech, whereby it calls itself the constitutional authority empowered to arbitrate institutional quarrels, interpreting, above all, its own constitutional competencies.