Partindo of the discussion on the impact of the decision of the STF invalidating the Herarense law on the vaquejé, the theory of contemporary constitutional interpretation is discussed. The search aims to check the reflexiveness of the legal system in the evolution of understanding of the meaning of the law in a political society. Taking Karl Popper’s thinking as a theoretical milestone, new proposals on interpretation, application and the need for critical thinking in legal practice are put forward. It makes it possible to distinguish between interpretation and application as a hypothesis, while also differentiating between the legal decision and a judicial decision. The aim is to reflect on contemporary problems of constitutional jurisdiction from a revalorisation of extra-judicial interpretation. It analyses elements of a possible interpretation with influences of so-called “critical rationalism”, especially with regard to Popper’s thinking about knowledge, interpreter bias and evolving interpretation theory. Finally, the results obtained in this research provide new premises for discussing a new understanding of the legal line of argument on the basis of a critical rational approach.