Gun-control activists protested over the weekend in front of a Starbucks in downtown Denver, saying that although Colorado law allows weapons to be carried inside Starbucks, or any other place of business, they think it's a dangerous policy (via CBS4). Tom Mauser, who lost his son in the Columbine massacre, says he'd like businesses to post signs saying weapons aren't allowed inside. The request comes as state lawmakers debate a gun-control measure that would mandate stricter background checks for buyers, according to 9News. Federal law prevents convicted felons from purchasing firearms, and Colorado fills a void with a program called InstaCheck to prevent sales to suspects facing possible conviction. The program is set to expire on July 1, 2010, but House Bill 1391 would make it permanent. The bill is facing some opposition from lawmakers concerned that it might violate potential buyers' constitutional rights. Senator Mike Kopp (pictured), a Littleton Republican, wants to keep guns away from criminals but says the bill goes too far, preventing purchases from people who have been arrested or charged with a crime but not convicted.