The social function of the contract: foundations, legal nature and effectiveness

Abstract

This article examines the principle of the social function of contracts in Brazilian civil law, based on art. 421 of the Civil Code and on the amendments introduced by Law No. 13,874/2019 (known as the Economic Freedom Act). It analyzes its legal nature as a general clause and a rule of public order, linked to the principle of sociality, as well as its role as a limit on private autonomy. The study addresses doctrinal critiques regarding the lack of precise conceptual boundaries and the difficulty of applying the principle autonomously. It also highlights its connection with the movement of constitutionalization of civil law and with the horizontal and diagonal effectiveness of fundamental rights, which reinforce the direct incidence of constitutional values in private relations. Finally, it emphasizes the dual effectiveness of the social function of contracts (internal, directed toward the contractual relationship itself, and external, aimed at preventing harm to specific third parties or to the community, as well as at avoiding undue interference by third parties that may frustrate its execution), demonstrating its importance for harmonizing contractual freedom with constitutional values such as solidarity and human dignity.