The court's 5-4 vote Wednesday leaves in place the initial trial court declaration that the ban is unconstitutional. California officials probably will rely on that ruling to allow the resumption of same-sex unions in about a month's time.
The high court itself said nothing about the validity of gay marriage bans in California and roughly three dozen other states.
The outcome was not along ideological lines.
Chief Justice John Roberts wrote the majority opinion, joined by Justices Ruth Bader Ginsburg, Stephen Breyer, Elena Kagan and Antonin Scalia.
"We have no authority to decide this case on the merits, and neither did the 9th Circuit," Roberts said, referring to the federal appeals court that also struck down Proposition 8.
The court invalidated a provision of the federal Defense of Marriage Act that has prevented married gay couples from receiving a range of tax, health and retirement benefits that are generally available to married people. The vote was 5-4.
Justice Anthony Kennedy wrote the majority opinion.
Same-sex marriage has been adopted by 12 states and the District of Columbia. Another 18,000 couples were married in California during a brief period when same-sex unions were legal there.
The court has yet to release its decision on California's ban on same-sex marriage.
"Under DOMA, same-sex married couples have their lives burdened, by reason of government decree, in visible and public ways," Kennedy said.
"DOMA's principal effect is to identify a subset of state-sanctioned marriages and make them unequal," he said.
He was joined by the court's four liberal justices.
Chief Justice John Roberts and Justices Samuel Alito, Antonin Scalia and Clarence Thomas dissented.
Scalia read his dissent aloud. Scalia said the court should not have decided the case.
But, given that it did, he said, "we have no power under the Constitution to invalidate this democratically adopted legislation."
NORTH ATTLEBOROUGH, Mass. (AP) - New England Patriots tight end Aaron Hernandez has been taken from his home in handcuffs after a Boston semi-pro football player was found dead in an industrial park a mile from his house.
Family members say the dead man, 27-year-old Odin Lloyd, was dating a woman whose sister is Hernandez's fiancee. Officials ruled the death a homicide but did not say how Lloyd died.
It's unclear why Hernandez was being taken into custody Wednesday morning and put into the back of a marked police car.
State police have searched in and around Hernandez's home in North Attleborough several times. At least three search warrants have been issued in connection with the investigation.
Hernandez attorney Michael Fee hasn't discussed the investigation.
LONDON (AP) - Second-seeded Victoria Azarenka has pulled out of Wimbledon after hurting her right knee in her opening-round win.
Early in the second set of her match against Maria Joao Koehler, Azarenka did the splits near the baseline, then crumpled to the grass, clutching her right knee and sobbing.
Azarenka recovered after a medical timeout to finish out the 6-1, 6-2 victory on Monday but she moved gingerly after falling and said she wasn't sure about the extent of the injury.
On Wednesday, minutes before her second-round match against Flavia Pennetta was to begin, she pulled out of the match.
Considered one of Serena Williams' toughest matchups, Azarenka has won the last two Australian Opens and had reached the semifinals in her last two Wimbledon appearances.