The Constitution has three main functions. First it creates a national government consisting of a legislative, an executive, and a judicial branch, with a system of checks and balances among the three branches. Second, it divides power between the federal government and the states. And third, it protects various individual liberties of American citizens.
1. Separation of Powers
The Government of the United States, the federal government, is divided into three branches: the executive power, invested in the President, the legislative power, given to Congress (the House of Representatives and the Senate), and the judicial power, vested in one Supreme Court and other federal courts created by Congress. The Constitution provides a system of checks and balances designed to avoid the tyranny of any one branch.
2. Division of Federal and State Power
Another important function of the Constitution is to divide power between the national government and the state governments. This division of authority is referred to as “federalism.” The federal government is very strong, with much power over the states, but at the same time, it is limited to the powers enumerated in the Constitution. Powers not delegated to the federal government, nor prohibited to the states are reserved to the states or to the people. Although the powers of the federal government are limited to those enumerated in the Constitution,
Because the United States Congress has been given the power to regulate interstate commerce, the states are limited in their ability to regulate or tax such commerce between them. Under the Constitution’s privileges and immunities Clause, states are prohibited from discriminating in many ways against citizens of other state.
3. Protection of Personal Liberty
The third main purpose of the Constitution is to protect the personal liberty of citizens from intrusions by the government. A few of these protections are found in the main body of the Constitution itself. For example, Article I, sections 9 and 10 prohibits both ex post facto laws, which punish conduct that was not illegal at the time it was performed, and bills of attainder which single out individuals or groups for punishment..
4. Permanent Protections of a Constitution
In a democracy without a written constitution, such as the United Kingdom, the legislature may pass laws granting or taking away any rights, or even changing the structure of the government itself. A Constitution is more difficult to alter, and the framers of the American Constitution made it especially difficult to amend. An amendment must first pass both houses of Congress by a two-thirds majority and must then be ratified by the legislatures of three-fourths of the states. In a sense, this makes the Constitution an anti-majoritarian document.
