295. Definition and Scope of Treaties. -- International Treaties or Conventions1 are agreements or contracts between two or more States, usually negotiated for the purpose of creating, modifying or extinguishing mutual rights and reciprocal obligations.____________________
The terms "treaty" and "convention" are practically synonymous, though the latter term is perhaps applied more frequently to treaties of lesser importance. There are various other kinds of agreements between States, such as protocols, cartels (see infra, note on p. 606), capitulations (see infra, pp. 606-07), the compromis (in arbitration, see infra, No. 310), declarations, modi vivendi (provisional working arrangements), exchange of notes or letters, and sponsiones, (agreements made between representatives who are not properly commissioned or who act in excess of authority).
Concordats are agreements between Catholic States and the Pope concerning the affairs of the Roman Church in Catholic countries.
The term protocol is used in a variety of senses. "Used to denote the form taken by an international compact, the word may be regarded as describing a somewhat informal record of an agreement between the High Contracting Parties.
"During a Congress or a Conference, . . . the minutes of the meetings of the plenipotentaries are styled either protocol or procés-verbal, indifferently. . . . Obviously protocol in this sense does not mean an agreement." 2 Satow, § 559.
Protocols are sometimes explanatory of the text of a treaty or are signed by way of fulfilment of a previous compact. Again the form may be used to record ratification or non-ratification of a treaty or to record compacts more or less independent of other international agreements, as, e.g. the Protocol of Agreement between the United States and Spain ( 1898) embodying the terms on which negotiations for peace were to be undertaken. For discussion and examples of these various senses in which the term "Protocol" is used, see 2 Satow, ch. 29.
For the three senses in which the term "Declaration" is applied, see Ibid., ch. 28. In the treaty sense Satow ( II, § 535) follows Oppenheim ( 1, § 487) in describing it as "the title of a body of stipulations of a treaty according to which the parties engage themselves to pursue in future a certain line of conduct. The Declaration of Paris, 1856, the Declaration of St. Petersburg, 1868, and the Declaration of London, 1909, are instances of this. Declarations of this kind, differ in no [Eessential] respect from treaties."
On Exchange of Notes and modi vivendi, see 2 Satow, §§ 584 ff. and 599 ff. See also 2 Hyde, §§ 508-09 and notes.