2004 Oregon Ballot Measure 36

Ballot Measure 36 was a 2004 initiative in the U.S. state of Oregon. It amended the Oregon Constitution to define marriage as a union of one man and one woman. The initiative passed with 1,028,546 votes in favor, and 787,556 votes against (57% to 43%) in the November 2, 2004 general election. It is one of a number of U.S. state constitutional amendments banning same-sex marriage. However, unlike other similar ballot measures passed on or near the same election date, the amendment did not explicitly ban civil unions between same-sex couples.

On May 19, 2014, the measure was declared unconstitutional by a U.S. federal district court judge, who ruled that it violated the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution.