John Lott, whose ground-breaking 1998 book “More Guns, Less Crime” exhaustively documented the way crime drops when local law is changed to require authorities to issue concealed firearm permits to all qualified applicants, made an interesting observation following the tragic Dec. 14 murders of 20 schoolchildren and six disarmed adults in Newtown, Conn.

Back in July, James Holmes, the accused Aurora, Colo., “Batman” killer of 12 theater-goers, had a choice of seven movie complexes within a 20-minute drive of his home that were premiering the “Batman” movie on which he was fixated.

The Cinemark Theater the killer ultimately chose was neither the largest nor the closest to his home, Lott told John Fund of the National Review Online, last week. (Actually, Lott first reported this at FoxNews.com, back in September.)

But the theater Holmes chose was the only one that posted signs saying it banned concealed handguns carried by law-abiding individuals with permits. All of the other theaters allowed the approximately 4 percent of Colorado adults who have a concealed-handgun permit to enter with their weapons.

The information could be learned with a few phone calls, Mr. Lott reports. The gunman was clearly willing to go out of his way to take advantage of the gun-free zone.

“Disarming law-abiding citizens leaves them as sitting ducks,” Lott told Fund. “A couple hundred people were in the Cinemark Theater when the killer arrived. There is an extremely high probability that one or more of them would have had a legal concealed handgun with him if they had not been banned” by the property owner.