&gt; The US Congress does, really, have line-item authority over regular US laws.<p>Except that, in this case, only if they first vote to change their own rules, which were set when TPA was passed. So they dig themselves a small hole, which they can jump out of without help. Nothing unconstitutional about that. Congressional-Executive Agreements are a pragmatic solution to a coordination problem, using constitutionally provided tools to solve a problem whose complexity was not envisaged by the authors.<p>Fun fact: the U.S. avoids entering into treaties which override our laws, despite explicit constitutional language which says that they would. Best to change laws by statute, so everyone is clear, and everyone doesn&#x27;t have to do a bunch of supremacy analysis.  We&#x27;ll even pass implementing legislation for treaties that in other nations are self-executing.