Legal Consequences of Agreements that have been Agreed and Not Implemented in Good Faith

According to Article 1338 of the Civil Code paragraph (3), namely: "An agreement must be carried out in good faith". The definition of good faith itself is an abstract meaning and difficult to formulate, so that it causes ambiguity regarding the meaning of the article. To what extent is the meaning contained in the principle and the legal consequences that arise if good faith is not implemented in the agreed agreement and the application of good faith in an agreement provides justice, legal certainty and benefits to the parties. The first problem, what is the meaning of good faith in the provisions of Article 1338 paragraph (3) of the Civil Code? Second, what are the legal consequences of an agreement that has been agreed upon and is not implemented in good faith? The research method used in this thesis research is to use a normative legal research type with a problem approach, namely a statutory, conceptual and case approach. The results of this thesis research are that the meaning of good faith according to Article 1338 paragraph (3) of the Civil Code is not explicitly explained therein. But overall the meaning explained by the experts, the meaning of good faith is about propriety and morality. The legal consequences of an agreement that has been agreed upon and not carried out in good faith is because it does not meet the valid requirements of an agreement in article 1320 of the Civil Code regarding "a matter prohibited by law" the requirement is an objective requirement then the legal consequence is that the agreement is null and void.