Pennsylvania on Tuesday became the fourth state in two weeks to have its gay marriage ban struck down as unconstitutional.
U.S. District Court Judge John Jones ruled the state's law barring gay marriage violated the Equal Protection and Due Process clauses of the Constitution and permanently restricted its enforcement.
"We are better people than what these laws represent, and it is time to discard them into the ash heap of history," he wrote in the ruling.
"By virtue of this ruling, same-sex couples who seek to marry in Pennsylvania may do so, and already married same-sex couples will be recognized as such in the Commonwealth," he added.
The ruling could be appealed to the Third Circuit Court of Appeals. Republican Gov. Tom Corbett's office did not immediately say whether it would appeal the decision, noting it is still being reviewed.
The judge ruled the state failed to prove the marriage laws were related to an important government interest, noting that "we, too, are unable to fathom an ingenuous defense saving the Marriage Laws from being invalidated under this more-searching standard."
"We now join the twelve federal district courts across the country which, when confronted with these inequities in their own states, have concluded that all couples deserve equal dignity in the realm of civil marriage," he wrote.
Pennsylvania, with Republican majorities in both state houses and in the governor's office, was one of the only Northeastern states that still had an active gay marriage ban enacted.
Gay marriage advocates have a perfect record in court rulings in the last year. Tuesday's ruling follows a decision in Oregon on Monday that made it the 18th state in the nation to allow same-sex marriage. Judges in Arkansas and Idaho struck down their states' gay marriage bans last week, but they have been delayed pending appeal.
In all, appeals are working their way through the courts in six states where judges have struck down bans but have stayed those decisions. In four other states, judges have ruled against laws that prevented their state from recognizing gay marriages performed in another state.
The American Civil Liberties Union helped file the lawsuit last year shortly after the Supreme Court issued its ruling invalidating a portion of the Defense of Marriage Act. The suit on behalf of 21 plaintiffs, some seeking to marry in the state, others looking to have their out-of-state gay marriages recognized, was one of the first filed after the high court's ruling.
Similar to a number of other states, Pennsylvania Attorney General Kathleen Kane has resisted defending the law, believing it is unconstitutional after the Supreme Court's decision. However, the governor had taken up the defense of the 1996 law, which defines marriage between one man and one woman.
—Updated at 4:05 p.m.