II, § 2, of the U.S. Constitution provides 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.” Thus, under the Constitution, an international agreement, concluded by the United States with another nation, in written form, and governed by international law—factors sufficient to make the instrument a treaty pursuant to the Vienna Convention requirements—is not a “treaty” in the domestic sense unless two-thirds of the Senate gives its advice and consent to the document. We will further address treaties and U.S. law later in the chapter, but first we need further to develop the concept of treaties in the international realm.
In the international sphere, in order to decide what constitutes an “international agreement,” one must first analyze the text. Ultimately, whether an instrument is a treaty depends on the intent of the parties. Thus, when there is doubt as to whether an instrument is a treaty, one analyzes the negotiating history, the formalities observed, and the expectations induced. The more formal the process, and the more formal the law-making authority of the government involved, the stronger the case for finding an “agreement.”
Treaties share critical characteristics as parliamentary and contractual instruments. For example, in terms of “who” can enter into a treaty, treaties are similar to domestic laws because only sovereigns can make treaties. On the other hand, like contracts, treaties apply only to those who are signatories.
Having first defined treaties and then described some basic characteristics, it is important to turn to the rules applicable to treaties that are set out in the Vienna Convention. The Convention is considered a codification of existing customary law.11 Therefore, non-signatories may be bound to its terms. For example, the United States has signed, but the Senate has not given its advice and consent to, the Vienna Convention. Yet the U.S. State Department has acknowledged that the United States is bound to its terms as they reflect binding customary norms.12
Because this is a volume on trade and human rights, it is important to emphasize that the Vienna Convention’s definition of treaty limits those instruments to written agreements concluded between states. This definition excludes agreements between a state and a private entity, although, through interpretation, the definition has been modified in practice to include agreements between a state and an international organization because such organizations are considered subjects of international law. In all cases, it is only the trade compacts concluded between and among states that qualify as treaties.
It is also important to note at this juncture that not all agreements between states are necessarily treaties. To be treaties, the agreements must be governed by international law. Thus, an agreement between State A and State B for the purchase by State A of State B’s beef using a standard form contract of the meat trade will not be deemed a treaty. Similarly, the purchase of a building or a piece of land by a state, when the contract is subject to the law of the municipality or a third state, will not be deemed a treaty.
1.3 International Law-Making: Specific Provisions
Let us now turn to some provisions of the Vienna Convention to ascertain what determines whether an instrument is a “treaty.” Part II of the Convention lays out the requirements for the “Conclusion and Entry into Force of Treaties” with Section 1 addressing the conclusion of treaties and Section 2 addressing reservations.
Regarding conclusion of treaties, Article 6 of the Vienna Convention provides that all states have the capacity to enter into a treaty. To be a state in international law, an entity must satisfy four requirements: it must have (a) defined territory; (b) permanent population; (c) a government capable of controlling the territory; and (d) a government with the ability to enter into international relations.13 One significant article in the first section of the Convention is Article 18, which imposes on signatories an obligation not to act in a way that “would defeat the object and purpose of a treaty.”
Section 2, “Reservations,” articulates an important concept in treaty-making. Reservations are “unilateral statement[s] … made by a state, when signing, ratifying, accepting, approving or acceding to a treaty, whereby it purports to exclude or to modify the legal effect of certain provisions of the treaty in their application to that State” (art. 2(d)). Thus, reservations allow states unilaterally to modify the terms of a treaty or the legal effect of the terms of a treaty. However, the Vienna Convention prohibits reservations that are “incompatible with the object and purpose of the treaty” (art. 19(c)). To ascertain incompatibility, the analysis scrutinizes the reservation in light of the purpose of the treaty. Reservations that frustrate the purpose of a treaty are invalid, even if in theory a state can object to whatever it wants based on its sovereignty.
Articles 20-23 detail the rules regarding reservations, including, respectively, states’ acceptance of and objection to reservations, the legal effect of reservations, withdrawals of reservations and objections thereto, and procedural requirements in making or accepting reservations, including that they be in writing. A state decides whether it deems the reserving party a party to Convention. In essence, these details emphasize that contracting states want to keep alive the “basics” of the Convention. With bilateral agreements, for instance, a reservation is the equivalent of a counteroffer to a contract in U.S. domestic law. While going into further detail on reservations is outside the scope of this chapter, it is important to note that the processes of making reservations and of objecting to or accepting reservations leads to complicated analyses about what states are bound by what terms of a treaty. The complexity is underscored when parties to multilateral instruments make multiple reservations.
Part III of the Vienna Convention focuses on the “Observance, Application, and Interpretation” processes. Article 26 sets out a basic principle of international law: pacta sunt servanda, which means that parties are bound by treaties and have an obligation to perform their terms in good faith. Parties cannot invoke internal law as grounds to fail to comply with a treaty obligation (art. 27). Treaties are not retroactive (art. 28), are binding on parties within their entire territory (art. 29), and their terms are to be interpreted in good faith in accordance with “the ordinary meaning to be given to the terms of the treaty in their context and in light of its object and purpose” (art. 31(1)). Article 32 allows use of the travaux preparatoires—preparatory works—developed during negotiations to assist in the interpretation of treaties. Significantly, the allowance of the use of travaux preparatoires might be a disadvantage to states that did not participate in negotiation of the treaty but became signatories later, as their voices are absent from the travaux.
Two other parts round out the substantive provisions of the Vienna Convention: Part IV addresses “Amendment and Modification of Treaties” and Part V focuses on the “Invalidity, Termination, and Suspension of the Operation of Treaties.” Part V specifically articulates error (art. 48), fraud (art. 49), corruption of a state representative (art. 50), coercion of a representative of a state (art. 51), and coercion of a state by threat of use of force (art. 52) as grounds for invalidating a treaty.
Part V also contains two articles that are important for purposes of this work. One is Article 53, which provides that if, at the time that it is concluded, a treaty conflicts with a peremptory norm of general international law—a norm from which no derogation is permitted—the treaty is void. Related to Article 53 is Article 64, which provides that if a new peremptory norm emerges, “any existing treaty which is in conflict with that norm becomes void and terminates.”
The jus cogens principle is particularly relevant to this volume as it is a concept of critical importance in human rights law. A rule of jus cogens can be derived from custom and treaties but not from other sources. In early international law this principle was articulated by writers saying that a treaty would be void if it was contrary to morality or to basic principles of international law: a treaty could not override natural law. Jus cogens, thus, prohibits states from contracting out of peremptory norms that are deemed binding customary norms. The
