I don’t think there is a good constitutional objection to the 13th Amendment, so I have no scruples there. One might have a concern about empowering the U.S. government in any capacity, even the capacity to do good. These are indeed difficult questions, with no neat answers. In a debate I saw him do years ago, Walter Block took the view that regardless of constitutional procedure, which to him is secondary (if even that), what it boils down to is this: can group A intervene to make sure group B stops oppressing people? Does group A, even if a government, have the right to do the right thing? Put that way, Walter was OK with it.