Vice President Cheney signed on to a brief filed by a majority of Congress yesterday that urged the Supreme Court to uphold a ruling that the District of Columbia’s handgun ban is unconstitutional, breaking with his own administration’s official position.Cheney joined 55 senators and 250 House members in asking the court to find that the Second Amendment protects an individual’s right to possess firearms and to uphold a lower court’s ruling that the D.C. ban violates that right. That position is at odds with the one put forward by the administration, which angered gun rights advocates when it suggested that the justices return the case to lower courts for further review.In order to make his dramatic break with the administration, Cheney invoked his rarely used status as part of Congress, joining the brief as “President of the United States Senate, Richard B. Cheney.” It is a position he has used at times to make the point that he is sometimes part of the legislative branch and sometimes part of the executive.