LOS ANGELES --Mayor Daley says if the U.S. Supreme Court strikes down the ability of cities to regulate guns it would open a 'Pandora's box.'The high court is considering a challenge by some residents to Washington D.C.'s strict handgun ban. As they heard arguments Tuesday, some justices seemed skeptical that the Constitution would allow a complete ban on handguns. On Tuesday in Los Angeles, Mayor Daley and several California lawmakers expressed their support for a plan to require micro-stamping on some weapons. It would make them easier to trace. He also expressed his support for the Washington D.C. ban. "We can outlaw smoking in a bar so quickly, you cannot outlaw guns in America? And guns kill you so quickly," said Daley. "I'm alive because I once had to use a handgun to defend myself. That's why I am able to stand here," said Tom Palmer, plaintiff. The Supreme Court ruling is expected in June.