In the beginning President Obama approached the issue of gay marriage cautiously.
He had long supported civil unions. He had worked to repeal "Don't Ask Don't Tell" and he'd come out against the Defense of Marriage Act (DOMA) which denies federal benefits to same-sex couples legally married in their states.
But even when he became the first sitting president in May of 2012 to say that he thought gays and lesbians should be able to marry, he moved carefully.
When pressed by ABC's Robin Roberts he suggested that the issue should be left to the states. "I continue to believe," he said, "that this is an issue that is going to be worked out at the local level."
But his endorsement influenced a cascade of politicians to switch positions on the issue. Even though 30 states still had language defining marriage as between a man and a woman in their constitutions, by November three more states would authorize gay marriage.
By the time of his inaugural address the president was speaking in sweeping terms.
He said, "Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law--for if we are truly created equal, then surely the love we commit to one another must be equal as well."
For gay rights activists the president's words were deeply moving. "He made clear that support for the freedom to marry is not just important to gay people and our loved ones, but a central part of the American project, our journey toward liberty and justice for all," says Evan Wolfson of the group Freedom to Marry.
By February, as expected, Solicitor General Donald B. Verrilli Jr. filed a Supreme Court brief in US v. Windsor, the DOMA case. Verrilli reiterated the administration's position since February 2011 that the law is unconstitutional. Verrilli wrote that DOMA "denies to tens of thousands of same-sex couples who are legally married under state law an array of important federal benefits that are available to legally married opposite-sex couples."
But at the time, the filing deadline was approaching in another case before the Supreme Court that asked a much broader constitutional question. Hollingsworth v. Perry is a challenge to California's Proposition 8, passed in 2008, that defines marriage as between a man and a woman.
Buoyed by the language in the inaugural address, some gay rights advocates wondered if the Department of Justice would weigh in, even though the federal government wasn't an official party in the case.
"It would be very important for us, for the United States to make clear that this is a matter that affects the lives of all Americans, it's the Constitution for all America," said Theodore Olson, an attorney representing two gay couples challenging Prop 8.
On February 28, Verrilli filed a brief and opponents of Prop 8 were delighted. Verrilli had not called for a constitutional right to gay marriage, but he wrote, "the president and the attorney general have determined that classifications based on sexual orientation should be subject to heightened scrutiny for equal protection purposes." If the court were to agree with would mean that any law based on the classification of sexual orientation would face much tougher scrutiny from the courts.
Verrilli said, "Proposition 8's denial of marriage to same-sex couples, particularly where California at the same time grants same-sex partners all the substantive rights of marriage, violates equal protection. "