Within the modern debate of constitutionalism are brought concepts that have remained through the time around the Philosophy of Law, they are known as: legal naturalism and legal positivism. Those ideologies have allowed making a restatement of the nature and orientation of the Constitutional Theory and the way how it is applied in Constitutional States, hence opening the road to the so called New Constitutionalism. Therefore, this has changed the reading of the Constitution for the positive component of the rule is no longer the center of the legal law; furthermore, new elements such as the Constitutional Tribunal and the Weight formula have been introduced in order to make an axiological and legal naturalistic thinking of the law. Thus, it is shown how the reading of the Constitution plays a key role in modern issues, although it is still under construction.