The impossibility of denying the importance of Economics in our society and, specifically, in Law, is striking when we realise the precision of its tools, even starting from a human science to delimit the results of its studies. It is realised that, when using economic science together with legal science, a notorious dynamism is caused for the performance of the operators of the law with greater decision-making power in our legal system, that is, legislators and magistrates. However, using economics in law requires special care, given that the core of the former is the quantification of results, always seeking the lowest cost for the best solution to your dispute. Already, the second, there is a resolution of conflicts through justice, which, inevitably, removes a better result for the whole, generating some indignation by the delay in solving problems, especially in Brazil, as well as the lack of prognosis to avoid future divergences. Thus, we sought, through the philosophical and doctrinal bases of both sciences, to understand the role of Economics in Law, through the Law & Economics movement, in times of advancing Neoliberal thinking.