The Security Council Workaround: How the Iran Deal Can Become Legally Binding Via a UN Security Council Resolution
Since the United States has made clear that its “deal” with Iran will NOT be a binding legal commitment under international law, one wonders what all the fuss over the Iran Letter from US Senators was about. As Duncan explains in his great post below, there is little doubt that the President can enter into a nonbinding “political commitment” and withdraw from it without violating international law. Confusingly, though, Iran keeps talking as if there is going to be a binding international legal commitment.
The answer to this confusion appears to be that the US government plans to make a non-binding political commitment, and then take this commitment to the UN Security Council to get it “carved into marble” as a Security Council resolution that would be binding under international law. Jack Goldsmith explains in detail at Lawfare how this might happen, and why this is constitutional (if also kind of sneaky). The President gets to both avoid going to Congress AND get a binding legal obligation on Iran.
Of course, a future President could choose to withdraw or defy the UN Security Council resolution, but the legal and diplomatic costs would be much higher than withdrawing from a mere political commitment. Congress could also, unquestionably, override any domestic legal effects of a UN Security Council Resolution by passing a statute refusing to lift sanctions on Iran, or stopping the President from doing so. Diggs v. Shultz makes clear that a statute passed by Congress later in time than a Security Council resolution will have the force of law by operation of the last in time rule. But the legal and diplomatic costs for doing so would also be higher than for a mere political commitment or even a bilateral executive agreement.
So the Administration has a plan to avoid Congress and get its deal sanctified by international law. Pretty clever lawyering, although I (like Goldsmith) expect some serious political blowback from Congress.