Alcohol didn't cause the high crime rates of the 1920s. Prohibition did.

And despite the claims of U.S. Attorney Joseph E. diGenova and others, drug use isn't causing today's alarming crime rate in the District. Drug prohibition is.

More than half the 95 murders in the District this year are "drug-related," in the marvelously vague term used by law enforcement officials. DiGenova says, "It's a sign of the intense competition that exists among organizations in the neighborhood drug-dealing business."

But there is intense competition among businesses in many industries, and we don't see Chrysler executives putting out contracts on their rivals at General Motors or shootouts between Coke and Pepsi bottlers. Even the rise of anti-Japanese sentiment over the trade deficit hasn't led to murder, despite a few wistful allusions to atomic bombs by Rep. Jack Brooks and some of his colleagues.

No, murder seems to be part of market strategy only in businesses that are forced to operate outside the law -- drugs today, alcohol in the era of Prohibition.

As a resident of Northeast Washington, I'm very much concerned about crime in the District. I wish that the city government's regular promises to crack down on drug use could be effective. But they won't be.

There are two ways in which drugs lead to violent crime. First, many addicts have to steal to support a habit that costs about $100 a day. Many experts estimate that half the property crime in the country is committed by drug addicts seeking money to pay for drugs. D.C. Police Chief Maurice Turner estimates that an addict has to steal $600 worth of goods a day to support a $100-a-day habit.

But the heroin that an addict needs would cost only a dollar or two a day, hardly enough to turn to a life of crime. The high cost of heroin is a direct result of our drug laws, which restrict the supply of drugs and drive up the price. How many alcoholics turn to crime to pay for their habit?

Turner says that there would be a marked change in the drug-related crime rate if the daily price of a habit fell to about $10. It would fall more than that in the absence of drug laws.

Second, as diGenova notes, the drug business is marked by violent confrontations between rival entrepreneurs. Again, this is a direct consequence of the drug laws. Prohibition, like protectionism, drives up prices and profits for those in the protected industry, making the protection of market share far more crucial in the drug business.

But more important, drug dealers have already been declared outside the law. When they have a dispute, they can't hire lawyers and go to court as other businessmen do. Like bootleggers in the Roaring Twenties, their only recourse is to violence. Finally, of course, this very outlaw nature of the industry attracts violent people in a way that legal industries don't.

We can continue to launch new offensives against drug trafficking, a policy that serves mainly to move street markets a few blocks over and maintain the anti-drug bureaucracy. Or we can recognize that our drug laws do more harm than good. They make drug dealing the most profitable enterprise for young ghetto entrepreneurs.

They also promote the spread of AIDS. Researchers have just noticed that while half the heroin addicts in New York City are infected with the AIDS virus, not a single addict in Hong Kong has tested positive. The reason is simple: hypodermics and needles, which may not be sold to the public in the United States, are available in any drug store in Hong Kong, so there is little or no sharing of needles.

Finally, repeal of the drug laws would dramatically reduce crime in the District and in other large cities. Those of us frightened by urban crime should convey a simple message to our public officials: campaigns to discourage drug use are fine. But we should just say no to prohibition.

David Boaz is vice president of public policy affairs at the Cato Institute.