1. September 1996: Congress passes the Defense of Marriage Act, which bars federal recognition of same-sex marriage. President Bill Clinton signs it into law on Sept. 20.
President Clinton in a file photo from 1994.
2. April 2000: Vermont becomes first state to legalize civil unions.
3. Nov. 18, 2003: The Massachusetts Supreme Court rules in favor of same-sex marriage.
4. May 17, 2004: Massachusetts begins performing same-sex marriages.
5. November 2004: Eleven states pass amendments barring gay marriage.
6. May 15, 2008: California’s Supreme Court rules that the state constitution guarantees same-sex couples the right to marry.
7. November 4, 2008: Proposition 8, a constitutional amendment banning same-sex marriage in California, passes.
8. August 2010: Federal judges in California rule that the same-sex marriage ban is unconstitutional.
9. December 2010: Congress votes to repeal the military’s “Don’t Ask, Don’t Tell” policy and President Barack Obama signs it into law. The repeal goes into effect in September 2011.
10. February 2011: The Obama administration announces that it will stop defending DOMA in court challenges.
11. June 24, 2011: New York becomes the sixth U.S. state to allow same-sex marriage.
12. May 8, 2012: North Carolina votes in favor of a constitutional amendment banning same-sex marriage as well as civil unions for gay and lesbian couples.
13. May 9, 2012: Obama announces support for same-sex marriage.
14. November 2012: Maine, Maryland, and Washington become the first states where voters approve same-sex marriage, and Minnesota rejects a new proposed ban.
15. December 7, 2012: The Supreme Court announces it will hear two same-sex marriage cases.
16. March 26, 2013: The U.S. Supreme Court hears arguments on a case challenging the constitutionality of California’s Proposition 8.
Attorney Theodore Olsen (right), representing the same-sex couples, addresses the Supreme Court in Washington on March 26, 2013. Justices (from left) are Sonia Sotomayor, Stephen Breyer, Clarence Thomas, Antonin Scalia, Chief Justice John Roberts, and Justices Anthony Kennedy, Ruth Bader Ginsburg, Samuel Alito, and Elena Kagan.
17. March 27, 2013: U.S. Supreme Court hears arguments on a case challenging the constitutionality of DOMA.
18. May 2013: Rhode Island, Delaware, and Minnesota pass marriage equality laws.
19. June 26, 2013: The Supreme Court rules that the Defense of Marriage Act is unconstitutional.
Edith Windsor, 83, acknowledges her supporters as she leaves the Supreme Court March 27, 2013, in Washington, D.C. The Supreme Court heard oral arguments in the case Edith Schlain Windsor, in Her Capacity as Executor of the Estate of Thea Clara Spyer, Petitioner v. United States, which challenges the constitutionality of the Defense of Marriage Act (DOMA).