In the case of Moises Sanchez-Llamas v. Oregon, 2005, the United States Supreme Court ruled that a violation of the Vienna Convention on Consular Relations does not provide grounds for suppression of evidence or dismissal of charges in criminal cases. The defendant, Moises Sanchez-Llamas, was a Mexican national who argued that his rights under Article 36 of the Vienna Convention were violated when he was not informed about his right to contact his consulate after being arrested. However, the court held that even if there had been a violation it would not have affected either admission or exclusion rules regarding evidence in U.S courts and therefore could not be used as an argument for suppressing incriminating statements made by him during police interrogation. Furthermore, it stated that defendants must raise such issues at trial to preserve them for appeal.

In the dissenting opinion for Moises Sanchez-Llamas v. Oregon, Justice Breyer argued that the majority's decision undermined an important international treaty and weakened America's ability to demand similar treatment for its citizens abroad. He disagreed with the majority’s view that suppression of evidence was not a necessary remedy when police failed to inform foreign nationals of their right to contact their consulate after arrest, as required by Article 36 of the Vienna Convention on Consular Relations. Instead, he believed this requirement should be enforced in domestic courts because it is part of U.S law due to our ratification of this treaty. Furthermore, he contended that allowing such violations without any meaningful consequence would encourage law enforcement officials to ignore these obligations and thus harm U.S interests abroad.