“Treaties become part of the law of the land so I am not sure this would be true.”
Treaties do become the law of the land but they can’t conflict with the Constitution. It’s liberals who push the idea that they can supersede the Constitution because they are always looking for ways around the bits they don’t like. The whole “living document” argument is an attempt to get around the amendment process. But to the extent there is a conflict between a treaty and the Constitution the Constitution wins. Of course, given the way Roberts ruled in the healthcare case I no longer think anything is safe.
They do. Routinely. Lots of them. FedGov even enforces the terms of treaties that were not ratified.