He ought to change federal drug law rather than refuse to enforce it.

He ought to change federal drug law rather than refuse to enforce it.

Marijuana remains a Schedule I substance under that 1970 law, meaning that it has a high risk of abuse. "No more dangerous than alcohol" is still dangerous, given the destructiveness of alcohol-related disease and social ills like drunk driving. There's an industry related to mitigating alcohol problems, after all.

We tolerate drinking because most adults use alcohol responsibly, and by all means let's have a debate about cannabis given how much of the country has already legalized it under the false flag of "medical" marijuana. But an honest debate would not whitewash pot's risks.

A growing body of medical research shows that the psychoactive substance in marijuana may cause permanent cognitive damage when used by adolescents, such as impaired memory and learning. The drug can trigger psychotic episodes, especially among vulnerable late adolescents, and the price decreases and social normalization of recreational use will increase the number of underage potheads.

"Middle-class kids don't get locked up for smoking pot, and poor kids do," Mr. Obama added. Actually, almost nobody gets locked up for pot. Americans collectively smoke for three billion days a year and use has increased 38% since 2007, according to a Rand Corp. analysis of federal health survey data, yet there were merely about 750,000 marijuana-related "arrests" in the U.S. in 2012. In the official FBI statistics that can mean anything from a ticket or summons to a full booking.

Very few people are incarcerated for simple possession, which makes up about 88% of arrests. There are currently about 40,000 state and federal prisoners serving time for marijuana-related convictions, and most have violent criminal histories. Most judges must be persuaded that someone is a true danger to society to sentence prison for mere drug use.

Mr. Obama is also kidding himself if he thinks drug legalization will be a boon to the poor. His own history of drug use is well known, but most users aren't the privileged students of the Punahou School. Like all human vices, the misery of addiction is always worse for those who lack the resources and family support of the affluent.

Mr. Obama is now the President, not a stoned teenager riffing with his Choom Gang, and he might have set a better example. Parents trying to teach their kids to make better choices than getting high are at a disadvantage when the person in charge of upholding the law says breaking the law is no big deal.

If the President believes that marijuana prohibition is an injustice, he has an obligation to propose his own legislative reforms, instead of unilaterally suspending the enforcement of federal drug laws that don't fit his political agenda.

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