Ramsey goes through all the different ways in which the deal might become constitutionally valid, but concludes that it isn’t likely to satisfy any of them. Under the text and original meaning of the Constitution, a major international agreement like this one is probably a treaty that requires a two-thirds majority in the Senate for ratification. Obviously, no such thing is in the cards, given the opposition of nearly all Republicans, and even some Democrats. As Ramsey notes, most people today – particularly nonoriginalists – agree that some international agreements (usually trade pacts) can become binding through majority approval in both houses of Congress. But that isn’t likely to happen in this case either.
As Jack Goldsmith and Marty Lederman have argued, the deal could be legally valid without congressional approval if it is a nonbinding executive agreement. But that, of course, means that a future president (or even President Obama himself) could renege on it at any time. As Ramsey notes, the Iranians and other parties to the negotiations certainly seem to assume that it is a legally binding agreement, not merely a nonbinding commitment by Obama that can be repudiated whenever the president wants.
Like Ramsey, I think the best argument for the administration’s position is that Congress pre-approved the agreement in legislation passed in May, which provides for a congressional vote on lifting sanctions after an agreement, and allows Congress to, in effect, disapprove the deal if they can get a supermajority large enough to overcome a presidential veto. However, as Ramsey points out, it is unlikely that the May law applies to a legally binding agreement, as opposed to merely a nonbinding executive agreement.
I would add that there are also serious constitutional questions about whether Congress has the authority to preemptively approve an international agreement whose terms have not been set yet, and therefore remain unknown. That seems like an unconstitutional delegation of legislative power to the executive, though the modern Supreme Court is extremely permissive on delegation issues. The whole point of requiring congressional ratification of international agreements is to enable legislative scrutiny of those agreements’ terms, a purpose which is undermined by preemptive legislative approval.
In the short run, it may not matter much – from a practical point of view – whether the Iran deal is constitutional or not. The courts are unlikely to hear a case on this issue, and there is little the GOP-controlled Congress can do to prevent the administration from beginning to implement the agreement (though, as Ramsey notes, they can choose not to lift congressionally imposed sanctions on Iran).
In the slightly longer run, however, the constitutional objections to the agreement might make it easier for a future administration to repudiate it. Opponents of the deal could potentially begin laying the groundwork for such a move by taking the position that it will not be legally binding unless and until it gets affirmative congressional approval.
In addition to the fate of the Iran agreement – an extremely important issue in itself – there is also a larger principle at issue: whether the President can make legally binding international agreements on important issues without getting them ratified by Congress in some form. Even if you trust President Obama with such sweeping authority, you should think carefully about whether future presidents are going to be similarly trustworthy.
UPDATE: I have made a few minor stylistic changes to this post.