In constitutional democracies, the legislative branch establishes electoral rules. In Brazil, proportional representation has led to a lower house composed by multiple political parties, which has impaired the conditions for a deliberative formulation of electoral rules. Electoral accountability tends to correct parliamentarian conduct and the multiple interests represented in parliament confer democratic legitimacy to laws. Furthermore, a list of institutional actors (including minority parties) can challenge the constitutionality of electoral rules. Notwithstanding, the judicial branch has drastically interfered in electoral disputes by either laying down general and abstract rules, disregarding the law, or allegedly enforcing constitutional principles. As for immediate effects, judicial decisions such as the one that modified the electoral financing system have undermined predictability, interfered directly with the conditions for competition, and changed political balance.