The Brazilian Financial Law is based on the Constitutional Law, in order to allow the implementation of public policies. The human rights and social guarantees established in the Constitution must be respected. However, the lack of resources causes public agents to act rationally and efficiently. Therefore, the planning of public policies
is essential. In this article, we will discuss how the constitutional legislation has provided the Brazilian legal system with instruments that can facilitate the achievement of public policies. However, rational planning should not dispense with social participation in its formulation.