Jose Erneso Medellin was executed in Texas yesterday for murder despite an order from the International Court of Justice (which is charted by the United Nations), that the execution not go forward because he was deprived of a right to diplomatic assistance by Texas, and not given a rehearing on the issue as required by the ICJ.
The U.S. Supreme Court ruled 6-3 that Texas wasn't bound by the order because the applicable treaty wasn't considered self-executing by the Court, and rejected a subsequent stay of execution by 5-4 with Justice Stevens changing his vote. Stevens had urged Texas to do the right thing and obey international law without being compelled to by the federal courts. Stevens apparently didn't understand Texas.
The actions of Texas, combined with the U.S. Supreme Court ruling, effectively nullifies the U.S. treaty in which the U.S. pledges to give foreigners charged with crimes access to diplomatic assistance, destroys the authority of the ICJ in the United States, and further undermines U.S. respect for international law.
Previous rulings of the U.S. Supreme Court have taken a similar approach to other U.S. treaties. For example, the U.S. Supreme Court has previously upheld as lawful the arrest and subsequent conviction of a Mexican national unlawfully (under Mexican law, at least) kidnapped from Mexico by U.S. officials in violation of the process for extradition set out in a treaty between the United States and Mexico.
Foreign law students and professors often wonder why international law is only a small part of the U.S. law school curriculum compared to its role in European and Asian law schools. The answer is simple. In the U.S., the rule is that we usually ignore international law.