This article identifies the bases of the liability of the State to repair the damages caused by not signing the statal contract when it is under the obligation to do so in a public selection process. In order to do so, first I describe the foundations of the pre-contractual liability of the State, emphasizing in the causality by omission, and later abording the principles of good faith and legality as titles of imputation of this particular type of responsibility. To develop this idea, I found necessary to review the antecedents of the pre-contractual responsibility, investigating roman law to establish the antecedents some of the laws that govern this type of responsibility.