The U.S. Supreme Court has made it very clear that
1) Treaties do not override the U.S. Constitution.
2) Treaties cannot amend the Constitution. And last,
3) A treaty can be nullified by a statute passed by the U.S. Congress (or by a sovereign State or States if Congress refuses to do so), when the State deems a treaty the performance of a treaty is self-destructive. The law of self-preservation overrules the law of obligation in others. When you've read this thoroughly, hopefully, you will never again sit quietly by when someone -- anyone -- claims that treaties supercede the Constitution. Help to dispell this myth.
"This [Supreme] Court has regularly and uniformly recognized the supremacy of the Constitution over a treaty." - Reid v. Covert, October 1956, 354 U.S. 1, at pg 17.
This case involved the question: Does the NATO Status of Forces Agreement (treaty) supersede the U.S. Constitution? Keep reading.
The Reid Court (U.S. Supreme Court) held in their Opinion that,
"... No agreement with a foreign nation can confer power on the Congress, or any other branch of government, which is free from the restraints of the Constitution. Article VI, the Supremacy clause of the Constitution declares, "This Constitution and the Laws of the United States which shall be made in pursuance thereof; and all the Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme law of the land...’
"There is nothing in this language which intimates that treaties and laws enacted pursuant to them do not have to comply with the provisions of the Constitution nor is there anything in the debates which accompanied the drafting and ratification which even suggest such a result...
"It would be manifestly contrary to the objectives of those who created the Constitution, as well as those who were responsible for the Bill of Rights – let alone alien to our entire constitutional history and tradition – to construe Article VI as permitting the United States to exercise power UNDER an international agreement, without observing constitutional prohibitions. (See: Elliot’s Debates 1836 ed. – pgs 500-519).
"In effect, such construction would permit amendment of that document in a manner not sanctioned by Article V. The prohibitions of the Constitution were designed to apply to all branches of the National Government and they cannot be nullified by the Executive or by the Executive and Senate combined."