The debate over the legalization of same-sex marriage was long one of the most polarizing issues [JURIST op-ed] facing the American legal community. Several major cases shaped the course of the debate over the past 40 years.

Loving v. Virginia is a 1967 US Supreme Court case which declared laws prohibiting interracial marriage invalid. This landmark civil rights case is cited as precedent for many same-sex marriage cases. Plaintiff, Mildred Loving, made a speech [pdf] for the 40th Anniversary of the Loving case and compared the issues of interracial marriage and same-sex marriage:

I believe all Americans, no matter their race, no matter their sex, no matter their sexual orientation, should have that same freedom to marry. Government has no business imposing some people’s religious beliefs over others. Especially if it denies people’s civil rights.

Baker v. Nelson, is the first instance in which the Supreme Court faced the same-sex marriage. The Minnesota Supreme Court held that state law prohibiting same-sex marriage did not violate the Constitution. In 1972, the Supreme Court dismissed the appeal “for want of a substantial federal question.” This dismissal forced the lower courts to interpret the meaning of this unexplained decision regarding same-sex marriage.

In 1993 the Hawaiian Supreme Court held in Baehr v. Miike that discrimination based on sex is a violation of the right to equal protection guaranteed by the Hawaiian state constitution, and denying marriage to same-sex couples constituted discrimination. Currently, 35 states and the District of Columbia legally recognize same-sex marriage.

In the 1986 US Supreme Court case Bowers v. Hardwick, the Court upheld the constitutionality of a Georgia sodomy law. The court held that the Constitution did not confer a fundamental right upon homosexuals to engage in private sexual relations.

Next came Romer v. Evans, a 1996 case where the court overturned a Colorado constitutional provision because it discriminated against homosexuals, and violated the Fourteenth Amendment of the US Constitution. The Court held that “moral disapproval of homosexuality, animus towards gays and lesbians or simply a belief that a relationship between a man and a women is inherently better than a relationship between two men or two women, … is not a proper basis on which to legislate.”

On June 26, 2003, the US Supreme Court struck down state laws criminalizing private homosexual activity in Lawrence v. Texas, finding that such laws violate the Due Process Clause of the Fourteenth Amendment. This ruling overturned the Court’s previous decision in Bowers v. Hardwick.

In United State v. Windsor, the court ruled 5-4 that Section 3 of the federal Defense of Marriage Act (DOMA) was unconstitutional. DOMA defined marriage as between on man and one woman for purposes of all federal benefits. Therefore, legally married same-sex couples did not qualify for these benefits. Affirming the decision of the US Court of Appeals for the Second Circuit, the court ruled that Section 3 of DOMA violated the Equal Protection of the Fourteenth Amendment. The ruling did not create a constitutional right to same-sex marriage, but entitled couples in lawfully recognized same-sex marriages to certain federal benefits. Justice Anthony Kennedy’s opinion was joined by Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan.

On June 26, 2015, the Supreme Court handed down its decision in Obergefell v. Hodges [PDF], ruling that the Fourteenth Amendment requires that states license same-sex marriages and recognize same-sex marriages lawfully licensed and performed in other states.