News that Senator Schumer will seek the repeal of the open-ended authorization for our forces to use military action in Iraq throws into sharp relief one of our favorite constitutional questions: Who gets to make peace? One might think that’s an easy query. The power to declare war, after all, is granted in Article I, Section 8 to Congress. So all one has to do is repeal the Iraq War authorization, as Mr. Schumer proposes, and voilà.