The U.S. Postal Service and a Colorado man are arguing over where on postal property people can carry guns. Judges from the 10th U.S. Circuit Court of Appeals heard arguments yesterday in the case involving Tab Bonidy, a licensed handgun owner who sued the Postal Service over its ban on guns in post offices. The agency also barred Bonidy from leaving a gun in his vehicle in the parking lot. A federal judge last year ruled that the ban on firearms in postal parking lots violated the Second Amendment. But the agency can keep Bonidy from carrying a gun in the lobby. Both Bonidy and the Postal Service appealed. A Department of Justice attorney says it’s a safety issue. Bonidy says it is inconvenient to disarm just to pick up his mail.