Garcia - and the United States, who joined his petition - argued that he was entitled to a stay of execution because the International Court of Justice had held that arrests for foreign nationals must be accompanied by consular warnings. This ruling has been implemented in the United States by executive order, and is now the subject of pending legislation before the United States Senate.
The majority held that its prior decision in Medellín v. Texas, 552 U. S. 491 (2008), in which the Court held that neither the ICJ decision nor the President’s Memorandum purporting to implement that decision constituted directly enforceable federal law. It also declined to consider Garcia's potential remedies under legislation that had not yet been passed (and that has been pending for seven years.)
Justice Breyer dissented, and was joined by justices Ginsburg, Sotomayor, and Kagan. They wrote that Garcia's execution would place the United States in irreparable breach of its duties under international law.