violence and increase the risk of overdose. The recent history of the United States includes

two major periods of prohibition: federal alcohol prohibition from 1920 to 1933, and

the current war on drugs, which began in 1971. During both of these periods, we witnessed

increases in the homicide death rate that correspond to enforcement of these prohibitions.

Why do prohibitions lead to violence? First, we have to recognize that prohibiting the

production or consumption of a substance does not eliminate its use. Almost half of high

school seniors report using an illegal substance in their life. Prohibition merely drives the

market for drugs underground. Producers operate in a black market, and consumers conceal their

behavior. Economics predicts a variety of adverse effects

of black markets. The evidence confirms these effects. In a black market, when disputes

ariseóover sales territory, over product quality, over correct changeóthe legal system

is not available. Drug producers and consumers must resolve their own disputes and may rely

on violence to do so. The underground nature of black markets has

other negative effects. Consumers canít report their drug dealers to the Better Business

Bureau for having sold them low-quality cocaine. The lack of legal, visible options to impugn

the reputation of bad-faith drug dealers typically leads to lower quality, and importantly, less

predictable quality drugs, increasing the risk of poisoning and of overdose.

Further, law enforcement expends resources to enforce prohibitions. The time that police

officers spend chasing drug dealers and users is time not spent catching murderers, thieves,

or rapists. Prison space used to house drug dealers and users is space not available for

other, more serious criminals. One estimate suggests that homicide rates are 25 to 75

percent higher than they would be in the absence of drug prohibition.

If your goal was to reduce the consumption of marijuana, of cocaine, meth, or heroin,

there are other policy choices available. A policy regime such as the one we have with

tobacco of high tax rates, minimum smoking ages, and extensive education campaign, could

keep the consumption of these drugs relatively low while avoiding the violence and quality

issues associated with a black market. It might seem counterintuitive that prohibitions

are not the most effective way to reduce the consumption of a good, but economics points

out that prohibitions generate black markets, and black markets lead to other adverse effects.