Even if a drug is regulated, its consumption controlled through a system of medical prescriptions and taxed, it can easily find its way to the black market. Prescriptions don’t curb destructive behavior. Legalization doesn’t stop deaths or abuse, nor negate the necessity of prosecuting dealers. Legally prescribed drugs are now regulated the way many legalization advocates think illegal drugs should be. The flourishing black market in prescription painkillers and the thousands of deaths associated with their use demonstrate that drug use will not be magically fixed by regulating currently illegal drugs.
Perhaps this might be because recreational alternatives are…illegal! Criminalization creates incentives for doctors and patients alike to abuse the prescription system by artificially inflating the market price for, in this case, opiates, and then creating a mechanism by which people can get relatively easy accces to them. Why wouldn't this system be rife for abuse?
As for Mead's claim that legalization "doesn't stop deaths or abuse" and would cause "many more deaths from overdose" the evidence disagrees with him:
Portugal decriminalized possession of all drugs in 2001. The outcome, after nearly a decade, according to a study published in the November issue of the British Journal of Criminology: less teen drug use, fewer HIV infections, fewer AIDS cases and more drugs seized by law enforcement. Adult drug use rates did slightly increase — but this increase was not greater than that seen in nearby countries that did not change their drug policies. The use of drugs by injection declined.
And there's more:
Health experts in Portugal said … that Portugal's decision 10 years ago to decriminalise drug use and treat addicts rather than punishing them is an experiment that has worked. "There is no doubt that the phenomenon of addiction is in decline in Portugal," said Joao Goulao, President of the Institute of Drugs and Drugs Addiction, a press conference to mark the 10th anniversary of the law. The number of addicts considered "problematic" — those who repeatedly use "hard" drugs and intravenous users — had fallen by half since the early 1990s, when the figure was estimated at around 100,000 people, Goulao said.
Even if you're unwilling to accept that Portgual proves that legalize-and-treat will decrease drug abuse everywhere, it's overwhelmingly strong evidence that criminalization isn't the key variable in keeping drug abuse rates down. Given the horrific "externalities" associated with the drug war (read: mass murder), that should be reason enough to reconsider our failed drug policies.
(Chart of HIV/AIDS rates in Portugal by Greenwald [pdf].)