This paper argues against one of the premises on which relies the supremacy of the Constitution. This premise consists on the one-way process of interpretation comprehended in judicial review. In fact, it seems broadly accepted that the judgment of constitutionality is resolved only by interpreting the ordinary law according to the Constitution. We object that presumption. Instead, this article provides some reasons which proved the influence of the ordinary law on the process of interpreting the Constitution. In this sense, it could be said that judicial review is grounded on a bidirectional process of interpretation, because ordinary law affects the understanding of the Constitution and vice versa. The paper is focused in the abandoned aspect of that bidirectional process, which is the influence of the ordinary law on the interpretation of the Constitution.