a.) the United States Constitution
Montesquieu's work included "The Spirits of the Laws" where he saw two types of governmental powers existing: the sovereign and the administrative.
The administrative powers were the executive, the legislative, and the judicial. These powers should be separate from and dependent upon each other for check and balance.
Montesquieu's work highly influenced James Madison of Virginia known as the "Father of the Constitution". That is why the United States Constitution reflects the powers and responsibilities under each administrative power.
