WASHINGTON -- The Supreme Court made history Wednesday with two victories for marriage equality, in California and nationwide.

In a pair of highly anticipated decisions, the divided court effectively undercut California’s Proposition 8 and struck down a key portion of the federal Defense of Marriage Act. Though one of the decisions was written narrowly, together they provide an emphatic, if incomplete, win for advocates of same-sex marriage.

The decisions, issued on the final day of the term that started last October, address different issues. In each, a slim 5-4 majority rallied for the position that effectively supported same-sex marriage.

The Proposition 8 case involved a challenge to the California ballot measure that banned same-sex marriage. On Wednesday, the court concluded that the supporters lacked the legal standing to defend the measure.

Standing is the legal term for being eligible to file a lawsuit. To have standing, an individual must have a significant interest in the controversy and must either have suffered an injury or face an imminent threat of injury.

“Because we find that petitioners do not have standing, we have no authority to decide this case on the merits, and neither did the 9th Circuit,” Chief Justice John Roberts Jr. wrote.

The decision leaves intact a trial judge’s order blocking Proposition 8 from taking effect. At the very least, this means that two same-sex couples who filed the lawsuit against the ballot measure may marry. Advocates say that other same-sex couples in California should be able to take advantage of the ruling, though that might require further trial-level clarification.

The court’s majority, though, stopped short of declaring a constitutionally protected right to same-sex marriage nationwide. The justices also declined to take up the Obama administration’s proposal, which would have extended the ruling to a handful of other states that have shared California’s policy mix of allowing civil unions while banning same-sex marriage.

President Obama called the plaintiffs in the Proposition 8 case while they were on television being interviewed. "We’re proud of you guys,” he said.

House Speaker John Boehner released a statement about the decisions that reads, in part, "While I am obviously disappointed in the ruling, it is always critical that we protect our system of checks and balances. A robust national debate over marriage will continue in the public square, and it is my hope that states will define marriage as the union between one man and one woman." The separate Defense of Marriage Act case involved a challenge to the 1996 federal law that prohibited same-sex couples who’d been married under state laws from obtaining a host of federal benefits. A different majority concluded that portions of the law violated the Constitution.

“DOMA divests married same-sex couples of the duties and responsibilities that are an essential part of married life,” Justice Anthony Kennedy wrote. He joined the court’s four liberal justices in the decision.

Section 3 of the Defense of Marriage Act declares that, for the purposes of providing federal benefits, marriage is “only a legal union between one man and one woman as husband and wife” and a spouse is only a “person of the opposite sex who is a husband or a wife.”

The definition is important because it determines eligibility for a host of federal rights, benefits and privileges.