This paper discusses how predicates of Law and Economics, interdisciplinary approach, statistics an empirical methods of research in Law can improve the jurisprudence of the Brazilian courts. It analysis the concepts of private autonomy and social function of the rental or leasing contract through the study of cases of Brazilian courts, which are based on legal, economic and social aspects to decide matters in contract law. It is intended to demonstrate that the pursuit of efficiency does not conflict with justice and the principles of free enterprise, free competition and social function complement each other.
