This marks the first time in 40 years that the high court is being asked to fundamentally redefine what marriage is in the United States. In the process, the high court is injecting itself squarely into one of the most divisive social issues of the past quarter century.
The outcome could affect hundreds of millions of dollars in federal marriage benefits currently limited to heterosexual spouses.
As in 2003, gay rights advocates are again hoping to win the potentially decisive swing vote of Kennedy. They are also hoping that the substance of Scalia's impassioned constitutional analysis in his dissent back in 2003 holds true in 2013.
"Lawrence was a very important turning point. It removed a huge roadblock on the path to gay marriage," says Dale Carpenter, a University of Minnesota Law School professor and author of "Flagrant Conduct: The Story of Lawrence v. Texas."
The decision lifted a legal stigma surrounding homosexuality and – despite Kennedy's disclaimer – it established a constitutional foundation that has influenced every subsequent court decision involving same-sex marriage.
Specifically at issue before the high court this month are two meas-ures that seek to preserve the traditional definition of marriage.
The first is a 2008 ballot initiative in California known as Proposition 8, which defines marriage in the state constitution as a legal union of one man and one woman. The second case is a challenge to the 1996 federal Defense of Marriage Act (DOMA), which for purposes of federal benefits also defines marriage as a union of one man and one woman.
Lawyers challenging the measures argue that Prop. 8 and DOMA violate the rights of same-sex couples by treating them like second-class citizens. "With the full authority of the State behind it, Proposition 8 sends a clear and powerful message to gay men and lesbians: You are not good enough to marry. Your loving relationship is not equal to or respected enough to qualify to be called a marriage," writes Washington lawyer Theodore Olson in his brief seeking to overturn Prop. 8.