Recall that the sunset clause in the new NAFTA says, "each Party shall confirm, in writing, through its head of government, if it wishes to extend the term of this Agreement for another 16-year period." While the written confirmation comes from the "head of government," the clause doesn't say anything about how each Party should make the decision about this extension under its internal domestic process.
Over on Twitter, Jennifer Hillman said this in the context of a discussion about the sunset clause:
Agree--but this is why Congress should include a specific Congressional process for the "automatic" termination provision. The USMCA does not specify the domestic process that can be used to implement it. Congress should make sure of its involvement + set up specific procedures.
In terms of Congressional involvement, how about this. For the determination of whether the United States "wishes to extend the term" of the agreement, both Congress and the President will have a role, in the following way: The agreement will be extended unless both Congress and the President affirmatively decide not to extend. The President can make the decision on his/her own, with an interagency process to provide guidance; for Congress, an affirmative determination not to extend will be based on a majority vote in each chamber (that is, both the Senate and House have to vote for termination in order for there to be an affirmative determination not to extend).
