Josh Rogin reports that a “group of 47 Republican senators has written an open letter to Iran's leaders warning them that any nuclear deal they sign with President Barack Obama's administration won’t last after Obama leaves office.” Here is the letter. Its premise is that Iran’s leaders “may not fully understand our constitutional system,” and in particular may not understand the nature of the “power to make binding international agreements.” It appears from the letter that the Senators do not understand our constitutional system or the power to make binding agreements.

The letter states that “the Senate must ratify [a treaty] by a two-thirds vote.” But as the Senate’s own web page makes clear: “The Senate does not ratify treaties. Instead, the Senate takes up a resolution of ratification, by which the Senate formally gives its advice and consent, empowering the president to proceed with ratification” (my emphasis). Or, as this outstanding 2001 CRS Report on the Senate’s role in treaty-making states (at 117): “It is the President who negotiates and ultimately ratifies treaties for the United States, but only if the Senate in the intervening period gives its advice and consent.” Ratification is the formal act of the nation’s consent to be bound by the treaty on the international plane. Senate consent is a necessary but not sufficient condition of treaty ratification for the United States. As the CRS Report notes: “When a treaty to which the Senate has advised and consented … is returned to the President,” he may “simply decide not to ratify the treaty.”

This is a technical point that does not detract from the letter's message that any administration deal with Iran might not last beyond this presidency. (I analyzed this point here last year.) But in a letter purporting to teach a constitutional lesson, the error is embarrassing.