The emergence of written constitutions has led to various changes in social orders, such as the protection of fundamental rights and guarantees, previously not provided for in the constitutional text and difficult for the public authorities to ensure. With the decadence of judicial and positivist doctrines, elements have been inserted into the legal systems which aimed at making constitutional rules more effective and ensuring the enforcement of rights. In the meantime, the crisis of legislative law and of the legislative power opens up the practice of judicial activism as a means of resolving issues not expressly provided for in the fundamental rules. The aim of this work is to analyse the search for the effectiveness of constitutional rules and the thrust of judicial activism in Brazil, and to verify the consequences of such proactive conduct by the judiciary on the basis of the link between law and politics. The objective of this article has been achieved by analysing references to judicial activism and constitutes an exploratory search.