While 55 senators and 250 representatives have asked the U.S. Supreme Court to uphold a ruling that the ban is unconstitutional, Cheney's support marks a departure from his administration's official position on the matter, The Washington Post said Saturday.

The government's representative to the Supreme Court, U.S. Solicitor General Paul D. Clement, had previously stated that a lower court ruling on the matter could prove dangerous for federal gun-control efforts.

Nonetheless, Cheney invoked his seldom-used title of president of the Senate and signed a brief calling for the support of the judicial ruling.

The Post said the lower court found that the D.C. ban violated the Second Amendment rights of citizens, which allows them the right to possess firearms.