Who believed that the power of government should be divided among three branches: an executive branch, a judicial branch, and a legislative

Montesquieu.

Explanation:

He was a French philosopher during the Enlightenment Era. His ideas of separating the powers of a government into three branches were used by several modern Constitutions. These branches, all independently one from each other, would be controlled by a system of checks and balances between them.

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the answer is richard nixion