This article analyzes «Imperial Presidency» in US Constitutional Law from a historical and institutional perspective. This is firstly made from a philosophical foundation of American constitutionalism and secondly from an evolution of the Presidential government. These two parts try to answer the question about the limits of the Federal presidency. It should be noted that these are not enough, because the executive orders promote the President's role, allowing the US to become a powerful country. The conclusion of this work that the «imperial presidency» is opposed to the moderate republic of the Founding Fathers; the blur limits of the executive department always adjust to the political power facts and situations. © 2019 Universidad Nacional de Educacion a Distancia. All rights reserved.