The whole body of "law" in the United States is composed of rules or laws made by legislative bodies (Congress, state legislatures, city councils, etc.), of regulations that are established to implement (or administer) legislation, and of decisions of courts at various levels when people challenge or question the law or its implementation.

The Constitution of the United States provides the framework for all of our laws, and is the most fundamental statement of the rules which govern our society.

There are two procedures under the Constitution through which the United States becomes a party to international agreement. Those procedures and the constitutional parameters of each are:

a. Treaties

International agreements (regardless of their title, designation, or form) whose entry into force with respect to the United States takes place only after the Senate has given its advice and consent are "treaties." The President, with the advice and consent of two-thirds of the Senators present, may enter into an international agreement on any subject genuinely of concern in foreign relations, so long as the agreement does not contravene the United States Constitution; and

b. International Agreements Other Than Treaties

International agreements brought into force with respect to the United States on a constitutional basis other than with the advice and consent of the Senate are "international agreements other than treaties." (The term "executive agreement" is appropriately reserved for agreements made solely on the basis of the constitutional authority of the President.) There are three constitutional bases for international agreements other than treaties as set forth below. An international agreement may be concluded pursuant to one or more of these constitutional bases:

(1) Agreements Pursuant to Treaty

The President may conclude an international agreement pursuant to a treaty brought into force with the advice and consent of the Senate, the provisions of which constitute authorization for the agreement by the Executive without subsequent action by the Congress;

(2) Agreements Pursuant to Legislation

The President may conclude an international agreement on the basis of existing legislation or subject to legislation to be enacted by the Congress; and

(3) Agreements Pursuant to the Constitutional Authority of the President

The President may conclude an international agreement on any subject within his constitutional authority so long as the agreement is not inconsistent with legislation enacted by the Congress in the exercise of its constitutional authority. The constitutional sources of authority for the President to conclude international agreements include:

1. The President's authority as Chief Executive to represent the nation in foreign affairs;
2. The President's authority to receive ambassadors and other public ministers;
3. The President's authority as "Commander-in-Chief"; and
4. The President's authority to "take care that the laws be faithfully executed."