Answer:
The idea that a just and fair government must divide power between various branches did not originate at the Constitutional Convention, but has deep philosophical and historical roots.
Checks and balances operate throughout the U.S. government, as each branch exercises certain powers that can be checked by the powers given to the other two branches.
The Supreme Court and other federal courts (judicial branch) can declare laws or presidential actions unconstitutional, in a process known as judicial review.
In turn, the president checks the judiciary through the power of appointment, which can be used to change the direction of the federal courts
By passing amendments to the Constitution, Congress can effectively check the decisions of the Supreme Court.
Congress (considered the branch of government closest to the people) can impeach both members of the executive and judicial branches.
