Washington (CNN) -- The Obama administration on Thursday formally expressed its support of same-sex marriage in California, setting up a high stakes political and constitutional showdown at the U.S. Supreme Court over a fast-evolving and contentious issue.
In a broadly worded legal brief that senior government sources say had President Barack Obama's personal input and blessing, the Justice Department asserted gay and lesbian couples in the nation's largest state have the same "equal protection" rights to wed, and that voters there were not empowered to ban it.
"Prejudice may not," said the brief, "be the basis for differential treatment under the law."
But the administration specifically refused to argue that constitutional right should be extended to the 41 states that currently define marriage as between one man and one woman.
The justices will hear the so-called Proposition 8 case in March.
That case and another appeal over the federal Defense of Marriage Act will produce blockbuster rulings from the justices in coming months.
"The government seeks to vindicate the defining constitutional ideal of equal treatment under the law," said Attorney General Eric Holder. "Throughout history, we have seen the unjust consequences of decisions and policies rooted in discrimination."
"The issues before the Supreme Court in this case and the Defense of Marriage Act case are not just important to the tens of thousands Americans who are being denied equal benefits and rights under our laws, but to our nation as a whole," Holder added.