The leaders of the Rhode Island Bar Association have endorsed a proposal to allow gay and lesbian couples to marry. The association’s executive committee and its House of Delegates have both endorsed the legislation, which has passed the state House of Representatives. The Bar Association represents Rhode Island’s licensed attorneys. Rhode Islanders United for Marriage announced the association’s endorsement Monday. Ray Sullivan, the group’s campaign director, said gay marriage is an issue of justice and basic fairness. The proposal is awaiting consideration in the Senate.