The correct answer is separation of powers.
The US Constitution established three different branches within the federal government including:
1) The Legislative branch- This consists of the House of Representatives and Senate. These individuals are in charge of making laws.
2) The Executive branch- This consists of the Presidency and his/her cabinet members. These individuals ensure that the laws are being followed.
3) The Judicial branch- This consists of the Supreme Court. These justices are in charge of interpreting what the constitution means.
All three of these branches have the ability to override the actions of another branch. This ensures that no one branch has too much political power.