In what is viewed as a definitive statement of beliefs, the Obama administration filed a brief to the US Supreme Court opposing the marriage bans in Kentucky, Michigan, Ohio, and Tennessee. The constitution, said the administration, does not allow states to prohibit gay or lesbian couples from marrying.

The brief contained strong language declaring that laws against same sex marriage “impose concrete harms on same-sex couples and send the inescapable message that same-sex couples and their children are second-class families, unworthy of the recognition and benefits that opposite-sex couples take for granted.”

This is a milestone for Obama’s position on gay marriage. Although he is cited as supporting gay marriage in 1996, he distanced himself from those statements while running for Senator in 2004. It was not until 2012, after Vice President Joe Biden announced that he was ‘absolutely comfortable’ with gay marriage, that Obama told the nation that he supported gay marriage.

“At a certain point,” he said in an ABC interview, “I’ve just concluded that for me, personally, it is important for me to go ahead and affirm that I think same-sex couples should be able to get married.”

His administration has done much to extend equal rights to people of different sexualities, including repealing the military’s ‘don’t ask, don’t tell’ policy and banned discrimination based on sexuality in the federal civilian workforce.

“We are delighted with the fact that when the president took office, same-sex marriage was legal in two states, and it is now legal in 37 states and the District of Columbia,” said Valerie Jarrett, a senior advisor at the White House.

In Obama’s 2013 inauguration speech, he said “Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law.”

This session, the Supreme Court could take a major step on that journey by striking down state laws that ban gay marriage. Thursday was the deadline for people opposed to gay marriage bans to submit briefs.

The Obama administration’s brief was just one of many high-profile endorsements. The Human Rights Campaign delivered a brief that had been signed by over 200,000 people. Other supporters include “GOP officeholders, religious leaders and more than 300 of the nation’s largest companies — including the Super Bowl champions New England Patriots and the World Series-winning San Francisco Giants,” according to CNN.

People in favor of state bans on gay marriage have until the end of March to file their briefs.

The Supreme Court will begin to hear oral arguments on April 28.