The battle for same-sex marriage is likely to be the civil rights issue of this decade. Developments all over the world over the last several years have caused celebration, public outcry and passionate debate. In the last year alone, the first Latin American same-sex wedding was performed, Sweden joined the nations who allow same-sex marriage, and the United States saw the “Proposition 8” debacle in California, and the new federal lawsuits that will inevitably propel the issues toward the Supreme Court. The legal debate in the United States has asked the crucial question: is there a legal right to marriage for each person, regardless of sexual orientation? This article examines the debate through the prism of international law and argues that there is.

Scholars and courts have analyzed the constitutional, legal and moral implications of this debate. This article adds a new argument to the debate: same-sex marriage should be allowed in the United States because it is protected by customary international law, and U.S. courts do, and should, consider international custom in their jurisprudence.

Part One of the article details the myriad of areas in which “marriage” is a legally significant designation. Part Two describes the legislation, judicial opinions and contours of the debate in the United States to date. Part Three presents arguments for how same-sex marriage is protected by customary international law: it is protected through codifications of custom, it is a trend in at least parts of the world, and most importantly, the justifications of the nations who allow same-sex marriage evidence a sense of legal obligation to allow it. Part Four examines how the United States courts have used customary international law in a variety of cases, and explains how courts could incorporate those norms to find that same-sex marriage should be legalized. The article concludes with two essential appendices that illustrate the current status of same-sex marriage: a state-by-state current summary of the issue in the United States and a large selected nation-by-nation compilation.