Same-sex marriage was legalized today in the nation’s capital, making it the sixth US jurisdiction where the practice is legal.

The Religious Freedom and Civil Marriage Equality Amendment Act, which allowed same-sex couples to marry in Washington, was passed in December 2009, but because Washington is a federal district, the law had to undergo a congressional review until now.

Opponents of the bill filed court papers with Chief Justice John Roberts asking the Supreme Court to stop the law from taking effect so that they could hold a referendum on the issue. Roberts, however, denied the request, concluding that the “high court should defer to local matters in the federal district of Washington,” CNN reported.  He also stated that opponents can pursue a ballot initiative to give D.C. voters a chance to repeal the marriage act after it becomes law.

Currently, same-sex marriage is also legal in Connecticut, Iowa, Massachusetts, New Hampshire, and Vermont.