That has not been the way it has been handled.
Remember, most of what we call “law” is really “What have we done before?” In this case, settled law has been that treaties once ratified are considered binding even if they are in conflict with local/state/national laws.
Not saying I like that, but that there is a precedent.
In the case of the UN, they claim jurisdiction on all member nations. We (the US) and other allied nations set that up after WWII. That is why the US bombed Serbia for violating “International Law”.
I doubt the Serbs thought it was legal.
There have been and will continue to be numerous attempts to subvert our Constitution. Activist Judges will see their influence shortened permanently pretty soon.
Justice Black pointed out in that case that: The concept that the Bill of Rights and other constitutional protections against arbitrary government are inoperant when they become inconvenient or when expediency dictates otherwise is a very dangerous doctrine and if allowed to flourish would destroy the benefit of a written Constitution and undermine the basis of our Article VI of the Constitution only provides that treaties can be considered equal to U.S. statutes and laws when considered by the Court. However, they cannot be used to alter the U.S. Constitution, or to deny Constitutional rights to American citizens, or to the American states. Therefore, even if the U.N. Small Arms Treaty is finalized, signed by the President, and ratified by the U. S. Senate, it would not take away the rights of Americans to keep and bear arms under the provisions of the 2nd Amendment to the Constitution.