If the treaty does not retain a particular value as a political instrument, a promise that was made as an executive agreement of Congress is just as lasting as a promise made as a treaty. On the other hand, if the contracts are different qualitative promises, the average contract should survive the average agreement between Congress and the executive branch. In this way, theoretical debate leads to observable and verifiable empirical assertions. The second option is the executive agreement. Executive agreements can continue to be divided into different types. Congressional executive agreements require a simple majority in the House of Representatives and the Senate.Footnote 21 They are used in areas where the executive branch is not solely responsible. Congressional approval can be obtained after the agreement was negotiated, as was the case with the North American Free Trade Agreement (NAFTA) footnote 22 or the Uruguay Round agreements of the General Agreement on Tariffs and Trade. Footnote 24 The above discussions show that there are countless theories about the qualitative difference between contracts and congressional executive agreements. A common approach to solving these theoretical debates is to focus on empirical data.
However, as noted above, the theoretical literature and empirical literature do not appear to be conclusive, with the hypotheses of both categories supported by empirical quantitative evidence. 82 Hathaway, supra note 1, at 1259 (“[S]eparating executive agreements that are congressionally authorized from those that are not required a akribisch search for authorizing legislation. In order to determine whether an agreement is an agreement between Congress and the executive branch, it is necessary to go through The Statutes of Large before the effective date of the agreement for terms related to this topic. It is then necessary to read each statute to determine whether it actually approves the relevant international agreements. (Footnote omitted). It is possible to understand this ambiguity in the empirical results by observing that previous studies all follow a similar approach. The researcher analyzes the environment in which an international agreement has been reached and attempts to identify models that help predict the type of instrument used. If the model corresponds to a motivation that places different importance on the treaties and executive agreements of Congress, it is proof that these instruments differ in their quality. Thus, Martin concludes that contracts are used when the partner country has a high GDP per capita, that contracts are preferred when the stakes are high, and that they must therefore be more reliable engagement mechanisms than agreements between Congress and the executive branch.