'Embarrassing': GOP senators get the Constitution wrong while lecturing Iran about US law
Senator Tom Cotton of Arkansas speaking at the 2015 Conservative Political Action Conference (Gage Skidmore/Flickr)

An open letter signed by 47 Republicans senators warning Iranian leaders about a nuclear deal with the United States contains an "embarrassing" and "unbecoming" error.

“It has come to our attention while observing your nuclear negotiations with our government that you may not fully understand our constitutional system,” the letter began.

But Harvard Law School professor Jack Goldsmith, writing at the Lawfare blog, said it appears that the senators are the ones who "do not understand our constitutional system or the power to make binding agreements."

The letter warned that President Barack Obama had no right to negotiate international treaties without congressional approval.

"In the case of a treaty, the Senate must ratify it by a two-thirds vote... Anything not approved by Congress is a mere executive agreement," the letter claimed.

However, Goldsmith noted that the Senate's own website makes clear that the Senate does not "ratify" treaties. The president is the one who ratifies the treaty if the Senate consents.

"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," the Senate's website explains.

Goldsmith described the error as embarrassing.

"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... But in a letter purporting to teach a constitutional lesson, the error is embarrassing," he concluded.

Goldsmith wasn't the only one who spotted the inaccuracy.

Andrew C. McCarthy, writing at the conservative National Review, said the letter was a "step in the right direction," but also noted the senators' "unfortunate" error.

"Substantively, this is a small point. After all, many people understandably conflate consent with ratification, since a treaty cannot be ratified absent Senate consent. But when the point of a letter is to lecture people about our law, getting the law wrong is, shall we say, unbecoming," he wrote.