The constitutional text, democratic principles, and entrenched practice overwhelmingly support the binding character of the Iran agreement. So does legislation that Congress adopted last May, which explicitly grants the Administration authority to negotiate and implement binding legal commitments with Iran.

Other provisions of the May legislation reinforce the high seriousness with which Congress has taken the president’s initiative. The statute, in setting down the procedural ground rules for negotiations, required the president to give the House and Senate roughly 60 days to reject the terms of any settlement he might reach with the Iranians.

This represents a sharp departure from standard practice. Generally speaking, Congress finds it too time-consuming to pass judgment on the individualized deals that the executive negotiates with foreign governments. It instead allows them to go into effect immediately so long as they comply with the rules set out in the authorizing statute. Congress insists on case-by-case review only on matters of fundamental importance—it singled out these negotiations for special attention precisely because they could create a long-term arrangement,  lasting 15 years, that  will govern the conduct of several presidents.