International Law and Agreements: Their Effect Upon U.S. Law
Congressional Research Service 1
Introduction
International law consists of “rules and principles of general application dealing with the conduct
of [S]tates and of international organizations and with their relations inter se, as well as with
some of their relations with persons, whether natural or juridical.”
1
Rules of international law can
be established in three main ways: (1) by international, formal agreement, usually between states
(i.e., countries), (2) in the form of international custom, and (3) by derivation of principles
common to major world legal systems.
2
Since its inception, the United States has understood international legal commitments to be
binding upon it both internationally and domestically.
3
The United States assumes international
obligations most frequently when it makes agreements with other states or international bodies
that are intended to be legally binding upon the parties involved. Such legal agreements are made
through treaty or executive agreement. The U.S. Constitution allocates primary responsibility for
such agreements to the executive, but Congress also plays an essential role. First, in order for a
treaty (but not an executive agreement) to become binding upon the United States, the Senate
must provide its advice and consent to treaty ratification by a two-thirds majority.
4
Secondly,
Congress may authorize congressional-executive agreements. Thirdly, in order to have domestic,
judicially enforceable legal effect, the provisions of many treaties and executive agreements may
require implementing legislation that provides U.S. bodies with the authority necessary to enforce
and comply with an international agreement’s provisions.
5
1
RESTATEMENT (THIRD) OF FOREIGN RELATIONS, § 101 (1987). Recorded international law dates back to agreements
between Mesopotamian rulers five thousand years ago, but international law as we understand it began with the Roman
Empire, whose scholars formulated a jus gentium (law of nations) they believed universally derivable through reason.
See generally D
AVID J. BEDERMAN, INTERNATIONAL LAW IN ANTIQUITY (2001). The term “international law” appears to
have been coined by Jeremy Bentham in 1789. J
EREMY BENTHAM, AN INTRODUCTION TO THE PRINCIPLES OF MORALS
AND
LEGISLATION 326 n. 1 (Hafner Publ’g Co. 1948) (1789). Although originally governing State-to-State relations, the
scope of international law has grown, beginning in the latter half of the 20
th
century with the emerging fields of human
rights law and international criminal law, to regulate the treatment and conduct of individuals in certain circumstances.
See, e.g., Universal Declaration on Human Rights, UN GAOR, Supp. No. 16, UN Doc. A/6316 (1948); Geneva
Convention (Third) Relative to the Treatment of Prisoners of War, Aug. 12, 1949, 6 U.S.T. 3316, 75 U.N.T.S. 135;
Geneva Convention (Fourth) Relative to the Protection of Civilian Persons in Times of War, Aug. 12, 1949, 6 U.S.T.
3516, 75 U.N.T.S. 287; International Covenant on Civil and Political Rights, G.A. Res. 2200A, U.N. GAOR, 3
rd
Comm., 21
st
Sess., 1496
th
plen. mtg., U.N. Doc. A/RES/2200A (XXI) (1966). See also U.S. State Dept. Pub. No. 3080,
R
EPORT OF ROBERT H. JACKSON, INTERNATIONAL CONFERENCE ON MILITARY TRIALS 437 (1949) (arguing that crimes
against humanity were “implicitly” in violation of international law even before Nuremberg).
2
RESTATEMENT, supra footnote 1, § 102.
3
See, e.g., Ware v. Hylton, 3 U.S. (3 Dall.) 199, 281 (1796) (“[w]hen the United States declared their independence,
they were bound to receive the law of nations, in its modern state of purity and refinement”); Chisholm v. Georgia, 2
U.S. (2 Dall.) 419 (1793) (“the United States had, by taking a place among the nations of the earth, become amenable
to the law of nations”); see also Letter from Thomas Jefferson, Secretary of State, to M. Genet, French Minister (June
5, 1793) (construing the law of nations as an “integral part” of domestic law).
4
U.S. CONST. art. II, § 2 (providing that the President “shall have Power, by and with the Advice and Consent of the
Senate, to make Treaties, provided two-thirds of the Senators present concur”).
5
See, e.g., Foster v. Neilson, 27 U.S. (2 Pet.) 253, 314 (1828) (Marshall, C.J.) (finding that international agreements
entered into by the United States are “to be regarded in courts of justice as equivalent to an act of the legislature,
wherever it operates of itself, without the aid of any legislative provision. But when the terms of the stipulation import
a contract, when either of the parties engages to perform a particular act, the [agreement] addresses itself to the
political, not the judicial department; and the legislature must execute
the contract, before it can become a rule for the
court”), overruled on other grounds by United States v. Percheman, 7 Pet. 51, 8 L.Ed. 604 (1833). C
ONGRESSIONAL
RESEARCH SERVICE, TREATIES AND OTHER INTERNATIONAL AGREEMENTS: THE ROLE OF THE UNITED STATES SENATE, A
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