The popular American TV drama series Justified, now in its fourth series, concerns a trigger-happy US marshal called Raylan Givens who fights crime in his (modern-day) native Kentucky. Most episodes culminate in a shoot-out, in which a dim bad guy draws his weapon, but Givens draws faster and kills him. "I was justified," he tends to mutter to his aghast superiors. "He pulled first."

It's the spirit of the Old West, in other words, a time when everyone wore a pistol and being faster on the draw was more manly than being a peace-lovin' varmint. Some of that spirit seems to have gripped the people of Colorado in the wake of last Friday's heinous cinema massacre. Something must explain why 2,887 Coloradans reacted to the killings and woundings, not by begging for strict gun controls, but by heading for Guns & Ammo stores and getting tooled up themselves.

Their logic is simple but mad. "If ONE person inside that theatre [had been] armed, this situation would NOT have been as bad as it is," read a Facebook post. And if 20 people were armed? That would work, wouldn't it? Instead of a lone madman blazing away in a movie theatre, you could have lots of them shooting in the darkness, every gunslinger having a pop at everyone they reckoned was the baddie – each confident that, at all events, he'd be justified.

Moviegoers are now, understandably, on a hair-trigger of concern and paranoia about the people sitting next to them. Panic broke out in an Arizonan cinema when a drunkard, creating a disturbance during The Dark Knight Rises, was nabbed by security guards. How long until a similar rowdy is dispatched in a hail of bullets because he might have had homicidal intentions? The shooters would say they, too, were justified.

Arizona's gun laws are already so lax that you can keep a gun concealed in your car's glove compartment (but if you're pulled over by a cop, you have to mention the fact). Courses on concealing your weapon about your person are commonplace. More and more nervy, flickering-eyed citizens will soon be packing heat, looking to see if someone's about to beat them to the draw, as if 21st-century Denver were the OK Corral in 1881.

And just when you thought you'd heard enough twisted logic, you discover that, in Colorado, the death penalty can be given for first-degree murder – but the District Attorney decides whether to apply it after consulting the victims' families. This most crucial of all laws is decided, not by debate in Senate or Congress, not by referendum majority, but by the bereaved. We are in classic Western territory here, where vengeance is heroic, the Colt 45 rules and the law holds its hands up in despair – like William Holden, just before everyone is shot to hell at the end of The Wild Bunch.

j.walsh@independent.co.uk