THE rulings of the Supreme Court in last spring’s landmark affirmative-action and gayrights cases were less surprising than the reasoning used by some of the Court’s justices. In resolving constitutional questions, the Court routinely relies on arguments appealing to the constitutional text and government structure, to precedent and prudence. In Grutter v. Bollinger, however, which upheld the use of racial preferences in law school admissions, and in Lawrence v. Texas, which struck down Texas’s prohibition on same-sex sodomy, the Court drew an additional arrow from its quiver. Several justices chose to assess the constitutionality of purely domestic civil-rights and civilliberties policies against the yardstick of foreign practices, foreign court decisions, and broadly worded, incantatory international human-rights agreements. In Grutter, Justice Ruth Bader Ginsburg (joined by Justice Stephen Breyer) cited both the International Convention on the Elimination of All Forms of Racial Discrimination (which the United States has ratified) and the Convention on the Elimination of All Forms of Discrimination Against Women (which it has not) as evidence of an “international understanding of the office of affirmative action.” In Justice Ginsburg’s view, these international conventions provide the grounds for “temporary special measures aimed at accelerating de facto equality.” In Lawrence, Justice Anthony Kennedy prominently recurred to a friend-of-the-Court brief on foreign law and court decisions filed by Mary Robinson, the former U.N. High Commissioner for Human Rights, and to a key decision of the European Court of Human Rights.