CHICAGO- Recently, Mexican President Vicente Fox vetoed a bill passed by the Mexican Congress that would have removed criminal penalties for people caught with small amounts of marijuana or other drugs. This came after the Bush administration vigorously complained, predicting it would encourage Americans to pour southward as "drug tourists."

But that option is off the table for the moment. So Americans who want to get high without fear of going to jail will have to go some other place where cannabis can be consumed with impunity. Such as Nebraska.

As it happens, no fewer than 11 states on this side of the border have made the decision not to bother filling their prisons with recreational potheads. Among them are not only such states as California and Oregon, which you might expect, but states such as North Carolina and Mississippi, which you might not. About 100 million Americans live in places where pot has been decriminalized.

Maybe there are planeloads of college kids who travel to Maine or Minnesota to spend each spring break hitting a bong, but if so, it's a well-kept secret. In fact, the most noticeable thing about states that have decriminalized marijuana is that they're not - noticeable, that is.

Looking at these places, "you can't tell the difference from how many people use marijuana," says University of Maryland, College Park economist Peter Reuter. A 1999 report commissioned by the National Academy of Sciences found "there is little evidence that decriminalization of marijuana use necessarily leads to a substantial increase in marijuana use."

Not everyone is in complete agreement. Rosalie Pacula, co-director of the Drug Policy Research Center at the RAND Corp., says her research indicates decriminalization does tend to lead to higher use. But by her measures, the effect is small.

Laws are only a modest factor in the decision to use drugs or not - just as they are only a modest factor in the decision to smoke cigarettes or not. Most people don't even know if they live in a decriminalized state.

The evidence from abroad is not terribly scary either. The Netherlands has gone beyond decriminalizing pot: For years, the government has allowed the sale of small amounts of pot through special cafes known as "coffee shops." Yet easy accessibility hasn't made the drug any more tempting to the average person. Dutch adults and teens both are less likely to use cannabis than Americans.

So it's hard to see why the United States should mind if Mexico decides to go easy on potheads. A good deal of evidence indicates that the law wouldn't make much difference in the behavior of either Mexicans or Americans.

There are some clear advantages, though. By freeing cops from focusing on recreational marijuana users, governments can reallocate more resources to serious crime.

Of course, the Mexican measure would have decriminalized possession of other drugs too, including heroin, cocaine and amphetamines - something no American state has done. Wouldn't something so drastic produce an explosion of hard drug use?

Actually, no. Italy, Spain and Portugal have decriminalized personal use of all drugs, not just cannabis. But liberal laws don't necessarily lead to liberal behavior. Spain has one of the highest cocaine use rates in Europe - but lower than the rate in Britain, which has a much stricter approach. Italy, by contrast, is about average for the continent, but Portugal is well below average. On heroin, all three are on the high side, though not dramatically so.

That fact, however, may not reveal anything about the effects of drug policies. It's easy to assume that when you change the law, you change behavior with respect to drugs. But the process may go in the opposite direction. Spaniards may not tend to use more cocaine because they have a permissive law; they may have a permissive law because Spaniards tend to use more cocaine.

States and nations don't seem to lose anything when they stop treating drug use as a crime. But there are gains to be had: more police time to combat violent criminals, less need to build prisons and fewer young lives scarred by arrest and imprisonment for behavior that does no harm.

Some people are happy with Mexico exactly as it is. But it just might benefit from becoming more like Nebraska.