Today, Stimson and Sullum address the relationship between drug laws and violence. Previously, they compared drug legalization and decriminalization, debated the federal government's authority to raid local marijuana dispensaries, and discussed past substance use by successful politicians. Tomorrow, they'll present their ideal drug policies for the U.S.

Question: Would softening drug laws alleviate or worsen drug violence in the U.S. and Mexico?

Legalizing all drugs would not "alleviate" drug violence. But it may change the nature of the violence -- likely for the worse.

As the argument goes, if you legalize drugs, you take the risk out of transporting drugs from Mexico to the United States. That may or may not prove to be completely true in reality. And yes, there may be a grain of truth to the theory that because legalizing drugs would result in fewer turf battles between gangs, the exact types of violence we see daily on the streets of every major city may decrease slightly. But that theory goes only so far.

Let's consider some basic economic facts and put your drug decriminalization theory to the test, Jacob. It's true that the price of heroin, meth, coke, marijuana and other illegal drugs would come down because suppliers would no longer have to add in a risk premium. No doubt, Jacob, you will say that legalizing dangerous drugs would alleviate drug violence in both countries and that, like alcohol, drugs should be regulated and taxed.

Here's the rub, though: If you impose high taxes, a gray market will inevitably be created, and along with it will come violence. If you impose no taxes, and thus the price remains low, there will be rampant consumption and the predictable, attendant violence and social dislocation that go hand in hand with consumption.

There are myriad examples of gray markets for legal products where, not surprisingly, violence is necessary to secure financial gain. The criminal cartels of Eastern Europe built their fortunes on, among other things, the cigarette trade. Cigarettes are legal. Move a bit north (Russia), and there's a thriving criminal trade in luxury automobiles. Cars are legal. Terrorist groups in the Middle East pocket money from selling bootleg DVDs. DVDs are legal.

These products are all taxed and regulated, yet there's a violent and vibrant gray market for them. Criminals always find ways to make money to finance their enterprises. They will do exactly the same thing with "legalized" drugs. The violence will continue even if you legalize drugs; the players will just be different.

Any policy that makes consumption of heroin, coke, meth, LSD and marijuana go up dramatically in the population will, without a doubt, increase violence and create massive social dislocation.

Take Amsterdam, where there is easy access to drugs. Amsterdam is one of the most violent cities in Europe. When the supply of heroin increased there, the price dropped and the number of hard-core addicts grew substantially.

So while there will be some people who, as they do now, smoke marijuana a few times a week and hold down productive jobs, there will be many more who consume more of these dangerous drugs because there will be no threat of criminal sanction hanging over their heads. Crime and violence will increase exponentially. It would be like adding gasoline to a fire.

Charles "Cully" Stimson was a local, state and federal prosecutor, a military prosecutor and defense attorney, and a deputy assistant secretary of Defense. Currently, he is a senior legal fellow at the Heritage Foundation (heritage.org).

On Feb. 14, 1929, five men working for Al Capone, disguised as police officers, lined up six members of a rival gang run by George Moran, plus a bystander, against the back wall of a garage on Chicago's North Side. Moran's men died in a barrage of machine-gun fire and shotgun blasts.

The St. Valentine's Day Massacre was, in a sense, "alcohol-related," but not because the hit men were drunk. Capone and Moran were competitors in the black market created by alcohol prohibition, and in a black market, this is how competitors settle their differences.

The same phenomenon can be observed today. A 1989 study reported in the journal Contemporary Drug Problems looked at New York City homicides identified as "crack-related" and found that 85% grew out of black-market disputes, while about 7% occurred during crimes committed to support a crack habit. Only one homicide out of 118 involved a perpetrator who was high on crack. The most common motive for the black-market homicides was "territorial dispute."

This sort of thing simply does not happen in the current alcohol market, where disputes are resolved legally and competition is peaceful. Coors and Anheuser-Busch may fight vigorously for customers, but the fighting never escalates into gunfire. To the extent that other markets in psychoactive substances are characterized by violence, the blame lies with prohibition, not with the particular drugs being sold.

Prohibition persists, by the way, in Amsterdam, where the retail sale of marijuana is tolerated but large-scale distributors of cannabis and all sellers of "hard" drugs remain subject to arrest and prosecution. While it's true that Amsterdam has a relatively high homicide rate compared with other European cities, I don't think you can plausibly attribute that fact to all the pot-smoking, which at any rate is more common in the U.S. than it is in the Netherlands. The U.S., which has a decidedly stricter drug policy, has a much higher homicide rate as well.

Cully, your examples of violent "gray markets" in untaxed cigarettes, bootleg DVDs and what I assume are either stolen or untaxed cars reinforce my point about the cause of such violence: All of these products are contraband, meaning the trade in them operates outside of the law. Governments are well-advised to avoid taxing any product, including tobacco, alcohol and the currently illegal intoxicants, at such a high rate that a substantial gray market emerges.

You say, Cully, that failing to impose such heavy taxes also will result in violence because it will encourage more drug consumption. You seem to assume that drug consumption causes violence. That certainly was the impression created by press coverage of the "crack epidemic," but the truth turned out to be quite different. "The media and public fears of a direct causal relation between crack and other crimes do not seem to be confirmed by empirical data," the U.S. Sentencing Commission noted in 1995. "Studies report that neither powder nor crack cocaine excite users to commit criminal acts and that the stereotype of a drug-crazed addict committing heinous crimes is not true for either form of cocaine."

The relationship between drug use and violence is complex and not necessarily causal. But the drug most strongly associated with violence -- more strongly than crack, PCP or methamphetamine -- is alcohol, which nevertheless remains legal, and in my view, rightly so. Prohibition did not make drinkers any more peaceful, and it made the people who supplied them a lot more violent.

Jacob Sullum, a senior editor at Reason magazine and a nationally syndicated columnist, is the author of "Saying Yes: In Defense of Drug Use."