What does “Constitutional” really mean? The devil is in the details
However, I would note the following from Article VI of the Constitution of the United States of American which notes (in what is know as the â€œSupremacy Clauseâ€?):
This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.
So, whatever else one may think of the decision, it should be duly noted that it is wholly within the purview of the Court to interpret the way by which treaties signed and ratified are to be applied to US policy.
I suspect I will have more to say later.
Give that he is a professor of political science, I await his discussion with great eagerness, despite the partisan inclination that we all suffer because we are mere humans.