"The Constitution of the United States comprises the primary law of the U.S. Federal Government. It also describes the three chief branches of the Federal Government and their jurisdictions. In addition, it lays out the basic rights of citizens of the United States. The Constitution of the United States is the oldest Federal constitution in existence and was framed by a convention of delegates from twelve of the thirteen original states in Philadelphia in May 1787. The Constitution is the landmark legal document of the United States..."