THE COLORADO SUPREME COURT put some noses out of joint when it ruled unanimously this month that the University of Colorado's campus gun ban violated a 2003 state law that entitles residents with permits to carry concealed weapons.

One of those noses belonged to Abraham Nowels, a University of Colorado student who wrote to the Denver Post: "We're in the middle of midterms right now, and I can't think of anything I'd rather be focusing on than which of my fellow over-stressed, binge-drinking peers is carrying a concealed weapon into class with me." The Post agreed, pleading in an editorial for "legislators with enough gumption" to change the state's concealed-carry law and "give colleges the power they need to keep students safe."

To those with an emotional bias against guns, it goes without saying that more guns in private hands invariably mean more crime and violence. If the number of people carrying firearms on campus rises, then of course that campus is less safe: What could be more obvious?

But it isn't obvious at all.

While the University of Colorado spent much of the past decade resisting the state's concealed-carry law, Colorado State University complied with it. If the gun controllers are right, Colorado State should have seen a surge in crime, while its gun-banning sister institution should have been an Eden of security and lawfulness. That's not what happened. As Clayton E. Cramer and David Burnett write in a new monograph for the Cato Institute, "crime at the University of Colorado has risen 35 percent since 2004, while crime at Colorado State University has dropped 60 percent in the same time frame."

Something similar happened after the US Supreme Court's 2008 Heller decision striking down the longstanding gun ban in Washington, DC. The city's mayor predicted in dismay that "more handguns in the District of Columbia will only lead to more handgun violence," yet crime in the nation's capital plunged. Murder nose-dived to its lowest rate in half a century, falling from 186 in 2008 to 144 in 2009 to 132 in 2010 to 108 in 2011 -- a far greater decline, as economist John Lott points out, than in the rest of the country, or in cities of comparable size.

To be sure, correlation doesn't prove causation. But the experience of Colorado and DC should come as no surprise. There is by now so much evidence that higher rates of gun ownership lead to lower rates of crime that it isn't hard to fathom why fewer and fewer Americans want to ban handguns.ording to Gallup, just 26 percent of the public now thinks the private possession of handguns should be illegal -- down from 60 percent half a century ago. Roughly 1 of every 4 Americans reports keeping a gun to protect themselves or their homes. Having a gun makes many people -- for good reason -- feel safer.

How often firearms are used defensively is a much-debated question in American criminology. Respected studies over the years have come up with estimates that range widely, from more than 100,000 defensive gun uses annually to as many as 2.5 million. Whatever the number is, it clearly isn't trivial. An enormous amount of death, bloodshed, and suffering is prevented in this country by ordinary citizens with firearms.

That doesn't mean terrible things can't sometimes happen when a gun is used for protection. Trayvon Martin, an Orlando teen, was shot dead last month by a Florida man who claims he was acting in self-defense. Yet the teen carried nothing more deadly than a bag of candy, and police told the gunman -- a Neighborhood Watch patrol member -- not to follow him.

Such tragic tales inevitably draw the spotlight. Far more common, but far less likely to be played up, are cases where guns are used to scare off, resist, or thwart a genuinely dangerous criminal. For their Cato paper, Cramer and Burnett assembled nearly 5,000 news stories reported by the media between 2003 and 2011. Their catalogue includes instances of armed customers preventing a store from being robbed, of victims fighting off would-be rapists, of senior citizens defending against a home invader, of attempted carjackings foiled because the driver had a gun -- even of self-defense against deadly animals.

Of course, most defensive gun uses never make the news at all. As Cramer and Burnett observe, "Man Scares Away Burglar, No Shots Fired," is not a very compelling headline.

But with or without headlines, millions of Americans grasp instinctively that guns make us safer. For when honest citizens carry weapons, criminals are less likely to attack -- and those who do are more likely to fail.