The laws that govern man, as well as the concepts of justice and injustice, are entirely subjective. They are based on the concept of the majority -- or those elected by the majority -- writing our laws to reflect said majority's feeling on each given issue.
For that reason, our forefathers implemented a system that allows us to band together and modify our laws accordingly, or to adapt them to dramatic shifts in belief or majority opinion. The ratification process is there for the very purpose of addressing what you seem to believe may be newly found or superior laws elsewhere in the world. If/when such laws surface, or the opinion of the majority changes to reflect the supposed injustices, then the ratification process is the ONLY option you have to change our laws or amend the Constitution itself.
M: Ah, so we adapt superior law when we evolve to the point where we can see it is superior, and I guess it isn't absolutely true the that superior is better than inferior, it being that much closer to perfection.
p: Until then, the Constitution über alles, and your "superior" international laws can not, and should not, apply to any person on US soil.
If a foreign power is ever granted the power of law over U.S. persons on U.S. soil, I will participate in the armed revolution that follows.
M: Great, everybody should have a revolution where they fight to keep superior law from applying. This shows real intelligence.
p: Exhibit A:
Some people believe that justice is served when a drug dealer is placed behind bars, while others believe that doing so is a tragic injustice. Still others believe the answer lies somewhere in the middle between punishment and the lack thereof.
How can you claim that such opinions of justice are anything other than subjective?
M: Superior vision. None of those alternatives is justice. They are just opinions. Serving justice is something that egos do to pat themselves on the back, to flatter themselves they have done the right thing. Justice exists only where there is love and one can't love two masters.