The Constitution divides Federal power into three (3) branches which are: the Executive, the Legislature and the Judiciary.
The Legislature is given the duty of making laws that are in line with the Constitution and the Judiciary is given the duty of interpreting the Constitution to ensure that the actions of the Executive and the Legislature do not violate it (Constitution).
The Executive is then given the duty of enforcing the laws passed by the Legislature as well as the Constitution. They do this through the various departments under the President that form part of the President's cabinet.
This ensures that no single branch has absolute power in the management of the nation's affairs.
The Civil War started because of uncompromising differences between the free and slave states over the power of the national government to prohibit slavery in the territories that had not yet become states.
