The two most important aspects of the United States Constitution are the separation of powers and the system of checks and balances between the different branches of government, and the Bill of Rights.

The separation of powers is of vital importance because it is designed to prevent the United States from becoming a tyranny. Checks and balances which limit the powers of the President, Congress, and the courts are intended to ensure that no one person or group is ever above the law.

The Bill of Rights consists of the first ten amendments to the Constitution. The first amendment is particularly vital, since it protects freedom of speech and freedom of religion. The fourth amendment is also important, as it protects against search and seizure. The government may only conduct searches with a warrant based on probable cause and issued by a judge. The fact that the executive branch must apply to the judicial branch in this case is another instance of the checks and balances between the three powers.

The fifth amendment provides for due process of law, while the sixth ensures the right to trial by a jury of one's peers. The ninth amendment enshrines in the Constitution the vital principle that this list of rights is not exhaustive and that the people have all rights not listed which are not specifically prohibited by other laws.