WASHINGTON (Reuters) - The District of Columbia's city council voted on Tuesday to decriminalize marijuana in a move that would make smoking a joint in the U.S. capital a violation comparable to a parking ticket.

The bill passed 11-1 in the first of two council votes. The second vote will take place at the council's next legislative meeting, due on February 18. To become law, it must also be approved by Democratic Mayor Vincent Gray, who has voiced support for the measure.

If the measure gets final approval, Washington would join 15 U.S. states and a handful of cities that have removed the threat of arrest for possession of small amounts of marijuana

Supporters have portrayed decriminalization in Washington as a way to cut law enforcement costs and increase fairness. A study by the American Civil Liberties Union has shown that eight times more black people are arrested for pot possession in the nation's capital than people of other races.

(Reporting by Ian Simpson; Editing by Cynthia Johnston and James Dalgleish)