The U.S. Constitution is one of the oldest in the world. It was adopted in 1787 by the Convention gathered in Philadelphia. The U.S. Constitution is the "oldest" of a written constitution in force at present. The U.S. Constitution consists of a preamble, seven articles, divided, in turn, into sections, and the amendments to the Constitution.
The U.S. Constitution is based on the principle of separation of powers in its "hard" version. Article I of the Constitution is devoted to the legislative authority (the U.S. Congress), Article II is the executive (President), Article III is the Judicial (mainly the U.S. Supreme Court.) Desire to ensure that their balance is carried out by clear separation of powers between the state, the establishment of a system of checks and balances of powers and their interdependence. The activity of the President and the Supreme Court is based on the laws of Congress, but on the other hand, the President has the right to veto laws, and the Supreme Court may declare laws and acts of the President unconstitutional and thereby paralyze their action. The president's authority extends to the Supreme Court: the President appoints its members, but with participation of the legislature, as these appointments are subject to approval by the Senate (2/3).
With such a system, the U.S. government mechanism works smoothly and effectively for more than two centuries. It is unknown crises and symptoms of abuse of power in one of its branch. However, we recall that this efficiency depends on the two-party system, which is adapted to the election and all the functioning of the state machinery.
There is no need to change any of these articles in order to change society.