A federal appeals court has declined to reconsider striking down California's prohibition on same-sex marriage, increasing the likelihood that the issue will reach the Supreme Court.

The legal challenge to California's Proposition 8, which bans same-sex marriage in the state, has been winding its way through the courts since shortly after voters approved the initiative in November 2008. The San Francisco-based Court of Appeals for the 9th Circuit in February upheld a lower court's decision that Proposition 8 unjustly took away an existing right (the California Supreme Court ruled in 2008 that members of the same sex should be allowed to wed, resulting in thousands of gay marriages).

Now that proponents of the ban have lost their push for another hearing at the 9th Circuit, they have 90 days to petition the Supreme Court to take up the case. A lawyer representing the measure's sponsors told the Associated Press they absolutely intended to go to the nation's highest court.

The ruling is the latest in a recent series of court decisions relating to same-sex marriage. A federal judge in Oakland ruled earlier in May that the Defense of Marriage Act, a federal ban on same-sex marriage that prevented same-sex spouses in California from receiving some federal health care benefits, was unconstitutional. A week later, a federal judge in Boston reached a similar conclusion.