Policy intellectuals are buzzing about a new book by UCLA public policy professor Mark Kleiman—When Brute Force Fails. In it, Kleiman argues that the United States could reduce crime and imprison fewer people, if only it applied law enforcement in more rational ways.

Kleiman opens with the true-life story that set his thinking in motion. A judge in Hawaii was vexed that paroled felons under his supervision regularly flunked their drug tests. Of course, he had the power to end their parole and return them to prison. But this draconian penalty required extensive hearings and much delay. Instead, he hit upon an expedited process: Any parolee who flunked a drug test would get an ultra-expedited hearing—and spend that same night in jail.

The results were dramatic. The certainty of a small but instant punishment altered parolee behavior in a way that the highly uncertain threat of massive punishment never had.

Kleiman develops this story into a sophisticated theory of law enforcement: If people are certain they will be caught, they will not offend. That means the state can reduce criminality without building expensive prison cells—the reduction in crime is "free."

I called Kleiman this week to pose a question: If targeting suspects in this way is the secret to better policing, is it also the secret to better aviation security? For example, what if you invited travelers to fill out a form providing information that is valuable for targeting but ethnicity-neutral? For example:

How long have they lived at their present address?

How long have they worked at their present job?

How many flights have they completed over the past two years?

How old are they?

Do they have children?

Do they have an honorable discharge from the military?

Answers to questions like these could be used to develop a risk profile of each traveler. Travelers could then be sorted into grades, with the least risky among them subject to the lightest search. (If you are looking for a needle in a haystack, the first step is to get rid of as much hay as you can.)

Kleiman’s response poses a challenge to those of us who think that better risk-profiling can lead to greater security with less inconvenience to travelers.

"In criminal law, we’re not trying to get to zero crime. So we can play the odds. We can allow some crime to occur somewhere if that’s not the crime we are concentrating force against," he said. "If all you are trying to do is improve the odds against terrorism, there are lots of ways to do that. But counter-terrorism is a fault-intolerant environment. How hard would it be for al Qaida—or another terrorist group—to recruit somebody who fits the profile of a trusted traveler?"

To put that point in context, consider the case of New York City. When Mayor Rudolph Giuliani decided to use concentration tactics to eliminate the squeegee men at the city’s bridges and tunnels, he had to accept the likelihood of a slight increase in pick-pocketing elsewhere in the city. That was a risk worth accepting since the new certainty of arrest for squeegeeing guaranteed that squeegee activity would fall close to zero, allowing police rapidly to redeploy to the next problem area. The odds were further improved by the fact that the squeegee men could not coordinate with the pick-pockets.

But terrorists can—and do—coordinate. They can notice, for example, that people who have lived at an address for more than 5 years—or who have an honorable discharge—are not being asked to remove their shoes when they pass through airport metal detectors. And they can act on that information.

"If you’re trying to play the odds against somebody who’s playing the odds against you—that’s a much more difficult problem," Kleiman says. "In criminal law, the law enforcer can act strategically against unorganized groups of offenders incapable of coordinating. But concentration strategies can be defeated by an opponent capable of unitary action."

However, Kleiman agrees that the more data we can muster, the harder it becomes for that opponent to defeat us. It’s hard to play the odds against an opponent who can play the odds against you—but hard for him, too.

This is why ethnic profiling is useless. Al Qaida can recruit terrorists of any ethnicity. If those terrorists are not themselves radical Muslims, mutually beneficial agreements can be struck with terrorists of other backgrounds—much as the Soviets brokered deals between Palestiniani radicals and the Japanese Red Army in the 1970s. (Japanese communists perpetrated one of the bloodiest terrorist atrocities against Israel—the Lod airport attack in 1972.)

By stacking all the elements I mentioned above—age, length of residence, marital status, etc.—atop a couple dozen others, you can create a finely meshed screen that would allow more passengers to move through airports faster. There will be no 
return to the easy movement of the 1960s. However, smart odds-playing can make air travel less miserable for most of us. Trusted travelers would still have to pass through some kind of inspection. But by pre-inspecting the large majority of air travelers before they ever arrive at the airport, security officers could put the less-trusted minority through the more personal inspection regime that has so well protected Israel.

Less hay makes life more difficult for the needles.

To clear away the excess hay responsibly, Kleiman’s work reminds us, will require a lot of information. In itself, that information is not so sensitive. Do you care if United Airlines knows how many years in a row you have filed an income tax return? But enabling that information to be collected, checked and used will require travelers to show a little unity of their own—overcoming the interest groups that have thwarted sensible security until now, and demanding a security approach that treats the public’s time as an economic value.

Even in the recession year of 2009, some 710 million travelers departed from U.S. airports. When the economy returns to normal, that number will rebound closer to 750 million. Let’s assume that the typical traveler’s time is worth $50 an hour—not a heroic assumption. Every 30 minutes’ delay at the airport costs the nation’s economy almost $19 billion. That’s real money—enough to fund the entire state university system of California for a year. But because it does not show up as a cost to government—only as a burden on individuals and the companies that employ them—it’s treated as free.

Kleiman reminds us that prison is expensive, so prison time should be conserved whenever possible. The same is true for labor and the travel time that fritters it away.

If the idiotic measures put in place by the TSA after the underwear bomber achieve anything, they should at least remind us of that.