Although it could be months before the US Supreme Court issues its rulings, this week's hearings on California's Proposition 8 and the federal Defense of Marriage Act (DOMA) are already historic.
It marks the first time the high court has ever decided to take on gay marriage cases and it does so as multiple polls show support of marriage equality at an all-time high.
On Tuesday (26 March), arguments will focus on whether Proposition 8 violates the Fourteenth Amendment to the US Constitution. The ballot initiative banning gay marriage in California was passed by voters in the state in November 2008.
The lawsuit against the law was filed by the American Foundation for Equal Rights (AFER) on behalf of two California couples: Paul Katami and Jeff Zarrillo and Sandy Belzer Stier and Kris Perry.
'There is an opportunity here for the court to send a message that who we love is important and we should be treated equally under the law,' Perry said during a recent conference call with reporters.
Zarrillo, during the same call, said the case 'affirms the commitment that we have built and shared. While some people say (marriage is) just a word, that word is so important.'
The California couples will once again be represented in court by the unlikely legal team of Ted Olson and David Boies who had faced off against each other before the Supreme Court in the 2000 Bush vs. Gore case which resulted in George W. Bush becoming president of the US.
Olson told the Los Angeles Times this week that the case 'has changed my life a lot because I think this is so enormously important to so many people. When I talk about it I get very emotional. I found out that some people I never guessed were gay. Lawyers came up to me and disclosed that about themselves.'
On Wednesday (27 March), the court will shift its attention to DOMA, a federal law passed in 1996 that prevents the US government from recognizing same-sex marriages even in states where such marriages are legal.
Federal appeals courts in New York and Boston had ruled the law is unconstitutional - rulings appealed to the Supreme Court by the Republican leadership of the House of Representatives.
The justices have agreed to hear the New York case which was filed by Edith Windsor who sued because she was required to pay a $350,000 federal estate tax bill. The government does not recognize her marriage to her late wife Thea Spyer.
'If Thea was Theo, I would not have had to pay' those taxes, Windsor tells NPR. 'It's heartbreaking. It's just a terrible injustice, and I don't expect that from my country. I think it's a mistake that has to get corrected.'
The Republicans took up defense of the case when President Barack Obama instructed the Justice Department to no longer defend the constitutionality of DOMA.
Under DOMA, couples cannot file joint federal tax returns or receive survivor benefits if one spouse dies. It was passed by both houses of Congress by wide margins in 1996 and signed into law by then-President Bill Clinton.
Once oral arguments are concluded, the cases will be submitted for consideration. The Justices will vote at their private Conference on 29 March and a final decision is expected by the end of June.
There are several possible outcomes.
In the Proposition 8 case, if the court strikes down the law, it could do so in a way that affects California alone, or eight states that allow civil partnerships, or all 50 states.
Another possibility is the justices dismissing the case which effectively would make same-sex marriages legal in California again for the first time since a brief period in 2008.
In the DOMA case, the justices could rule that it is unconstitutional to deny federal benefits to same-sex couples in states where gay marriages are legal or they could take things a step further and invalidate the law completely.
Other possibilities are to uphold DOMA or to leave the lower court ruling intact which would invalidate the act in part of the country but leave the main legal issue of its constitutionality unresolved.