The events leading up to the book The Spirit of the Laws were a major influence on the content. The Reformation happened in 1517 and in the next century England had its Scientific Revolution. Men like Galileo and Sir Isaac Newton shaped the way of thinking about the world, physics, and solar system around us. They also had political and social thoughts. This period was known as the Age of Reason. These ideas helped the way that Montesquieu thought in writing his Spirit of the Laws. And later these ideas were presented in the U.S. Constitution as some of the 5 main principles. These principles were influenced somewhat by Montesquieu's views on law.
A subtle principle in Spirit of the Laws but very important idea in the U.S Constitution is the process of checks and balances. Montesquieu states that "To prevent this abuse, it is necessary, from the very nature of things, that power should be a check to power." This is still in the Constitution today and is often used in politics weekly. Congress can't make a law at first without consulting the executive branch of government. Later though Congress can make a bill or law with two-thirds majority in favor of the document at hand. This is an important principle because if it had not been made than the Framers would have the fear of one branch becoming to powerful and that would risk tyranny and that is what the Framers were trying to abolish.
The Constitution also contains another principle mentioned in Spirit of the Laws. Montesquieu states that "When the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty." This influential quotation led to the idea of separation of powers. The three branches of government each have their own responsibilities and powers as a branch. The colonists also feared tyranny if the government was to strong as one whole. Each branch has one main duty: executive-to enforce the laws, legislative-to make the laws, judicial-to interpret the laws.