Medellin v. Texas and Sanchez-Llamas v. Oregon were the first opportunities for the U.S. Supreme Court to speak in the voice of Chief Justice John Roberts on several of the biggest questions at the connecting points between the U.S. legal order and the rest of the world. In writing for the majority in these cases, the new Chief Justice sent signals to several different audiences about whether and how the United States will fulfill its international obligations. The messages differ markedly from those sent by the divided Court in Hamdan v. Rumsfeld, in which Roberts did not participate. Hamdan was widely (although not universally) perceived as a reaffirmation of the Court's historic role in ensuring that individuals detained under governmental authority have a judicial forum in which their legal claims – including treaty claims – can be determined. The Hamdan majority found reason to believe that Congress intended the United States to comply with the international laws of war embodied in the 1949 Geneva Conventions, and it interpreted those obligations in a way that contributed to the perception of observance rather than abrogation.

Medellin and Sanchez-Llamas presented core issues of treaty jurisprudence in ways Hamdan did not. They marked the conclusion of a decade-long sequence involving the effects in U.S. law of the Vienna Convention on Consular Relations and several other treaties providing for international adjudication of disputes arising under the Vienna Convention.