Article 78 of Mexico’s Commercial Code reads: “En las convenciones mercantiles cada uno se obliga en la manera y términos que aparezca que quiso obligarse, sin que la validez del acto comercial dependa de la observancia de formalidades o requisitos determinados.” In commercial agreements, each party is bound in the manner and on the terms in which it appears it wished to be bound, and the validity of the act does not depend on particular formalities or requirements.
Article 1832 of the Federal Civil Code applies the same principle to civil contracts, except where the law expressly requires a particular form.