In a pair of landmark decisions, the Supreme Court removed many of the barriers facing same-sex couples seeking equal protection in the United States.

In a 5-4 decision, the Court invalidated the central tenet of DOMA, the Defense of Marriage Act of 1996, pushed through by Republicans and signed into law by then-President Bill Clinton, as decision the former president has since said he regrets.

DOMA prevented the federal government from recognizing any marriages other than those between one man and one woman. Same-sex couples legally married in states that allow recognize same-sex marriages were barred from receiving federal benefits, like joint tax filing, survivorship benefits, immigration sponsorship, veterans' benefits and others.

The Obama administration declined to defend DOMA before the Supreme Court, so congressional Republicans mounted an expensive effort to support the measure.

They lost, and the Court ruled DOMA unconstitutional. "DOMA is unconstitutional as a deprivation of the equal liberty of persons that is protected by the Fifth Amendment," wrote Justice Anthony Kennedy in the majority opinion. "By seeking to injure the very class New York seeks to protect, DOMA violates basic due process and equal protection principles applicable to the Federal Government. The Constitution's guarantee of equality 'must at the very least mean that a bare congressional desire to harm a politically unpopular group cannot' justify disparate treatment of that group."

In essence, the Court ruled that DOMA is discriminatory, and the federal government showed no reason that same-sex couples should, in fact, be discriminated against. The case will likely have far-reaching consequences for any same-sex marriage cases that make it to the Court in the future.

"DOMA's principal effect is to identify and make unequal a subset of state-sanctioned marriages. It contrives to deprive some couples married under the laws of their State, but not others, of both rights and responsibilities, creating two contradictory marriage regimes within the same State. It also forces same-sex couples to live as married for the purpose of state law but unmarried for the purpose of federal law, thus diminishing the stability and predictability of basic personal relations the State has found it proper to acknowledge and protect."

The Court did not invalidate the entire law. A provision that prevents states from being forced to recognize same-sex marriages in other states still stands, at least for now, so states that have banned same-sex marriage will likely still not have to treat same-sex couples in the same way as heterosexual couples.

The federal government, however, will, and the change takes effect immediately. Any federal benefit or law that applies to married couples or marriages must now apply equally to legally married same-sex couples.

In a related ruling, the Court effectively struck down Proposition 8, the California law banning same-sex marriage. In another 5-4 decision, the Court determined that plaintiffs in the case who oppose same-sex marriage and support Prop 8 did not have "standing." That is, they had no legal grounds to challenge a federal judge's decision to overturn Prop 8.

The Court vacated and remanded a prior decision by the Ninth Circuit Court of Appeals, directing the lower court to deny the appeal. That means the last judgment that still stands is the 2010 ruling by U.S. District Chief Judge Vaughn Walker which deemed Proposition 8's ban on same-sex marriage unconstitutional.

It is unclear exactly when same-sex marriages will be able to resume in California. They were briefly legalized in 2008 before Prop 8 passed in November of that year. Walker's ruling two years later put a stay on the performance of same-sex marriages while appeals worked through the legal system. Now that the appeals process is over, that stay could be ineffective, or it could be ended within a few weeks, allowing same-sex marriage to continue.

However, the Supreme Court made no ruling on the legality of same-sex marriages themselves, so further suits or appeals could be forthcoming, which might delay the process.

Whatever the outcome in the near future, same-sex marriage advocates have won two decisive victories.