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So Representative Trey Radel, the Republican from Florida, a self-styled “conservative voice” in Congress, has pleaded guilty to a misdemeanor charge of cocaine possession. And Toronto’s city council has stripped Mayor Rob Ford of much of his power after it came out that he had smoked crack (never mind that Ford’s well-known drunken antics were not cause for such censure).

Rather than arguing whether such figures are hypocrites (Radel voted in favor of mandatory drug testing for food-stamp beneficiaries) or debating how they should attempt damage control (he’s also pledged to enter a substance-abuse program after paying a fine and receiving a year’s probation), let’s ask a more basic question: What’s so scandalous about casual drug use?

Yes, some substances are illegal (though as the case of marijuana shows, this status is subject to change). But absent other indicators of dangerous and antisocial behavior — like driving while intoxicated — why should snorting coke be treated any differently than, say, drinking a beer?

(MORE: 8 Things We Won’t Miss When Pot Is Legal Everywhere)

Prohibitionists typically deny the very possibility of responsible or voluntary use of currently illegal substances. They argue that drugs such as coke, heroin, ecstasy, methamphetamine and even marijuana are verboten precisely because they simply can’t be used casually. Any use either already constitutes abuse or quickly leads to it. “Drugs are not dangerous because they are illegal,” former drug czar William Bennett and former Health, Education and Welfare Secretary Joseph Califano wrote in a 2011 Wall Street Journal op-ed, “they are illegal because they are dangerous.”

Nearly 50% of people have tried an illegal drug at least once, yet most don’t repeat the experience. With cocaine, most who have tried it not only don’t go on to became addicts under even the most expansive possible definition of the term, they don’t even go on to become regular users.

According to the latest National Survey on Drug Use and Health, 14.5% of Americans ages 12 and older have tried cocaine at least once, but just 1.8% report using the drug recreationally in the past year. And just 0.6% have used it in the past 30 days, which would seem to be the minimal definition of a casual user.

The same pattern is true for heroin, which is typically talked about as magically addictive. Fear of the drug is surely one of the reasons why just 1.8% of Americans have ever tried it at all. But only 0.3% report using it in the past year and just 0.1% in the past month. That pattern simply shouldn’t be possible if these drugs were as addictive as commonly thought.

In the early 1970s, researcher Lee N. Robins led a study commissioned by the Department of Defense that followed tens of thousands of Vietnam War veterans as they returned to the U.S. Use of narcotics and heroin was rampant among soldiers stationed in Southeast Asia, with as many 20% showing signs of addiction. Yet during the first year back, “only 5% of those who had been addicted in Vietnam were addicted in the U.S.” and “at three years, only 12% of those addicted in Vietnam had been addicted at any time in the three years since return, and for those readdicted, the addiction had usually been very brief.” It wasn’t for lack of access to junk, either: half of the returning addicts said they’d tried heroin at least once since arriving back home.

As my Reason colleague Jacob Sullum has documented, such take-it-or-leave-it findings are common in drug research. In his 2004 book Saying Yes and other places, he’s detailed work in which researchers find a surprising range among heroin users, including a study that concluded, “It seems possible for young people from a number of different backgrounds, family patterns and educational abilities to use heroin occasionally without becoming addicted.”

It’s also true that regular drug users can often function quite well. Sigmund Freud used cocaine habitually for years, and his first major scientific publication was about the wonders of the drug (he eventually forsook it). Another pioneering late 19th and early 20th century man of medicine, William Halsted, was dependent on cocaine and morphine during an illustrious career that revolutionized and modernized surgical techniques.

None of this is a brief for snorting cocaine, shooting heroin or smoking marijuana (a substance that 58% of Americans think should be legal for recreational use) any more than it is a plea for drinking single-malt whiskey or pinot noir.

But in an age in which we are expected to use legal drugs (like beer) and prescription medications (Adderall) responsibly, it’s time to extend that same notion to currently illegal substances whose effects and properties are widely misunderstood. Indeed, the effects of coke, heroin and the rest are a mystery partly because their outlaw status makes it difficult both to research them and have honest discussions about them.

(MORE: Give Rob Ford Rehab, Not Ridicule)

Radel has announced that he’ll be taking a leave of absence from Congress while he enters rehab. Perhaps he does need to sober up — that’s really for him and his family to decide — but it’s far from clear that his problem is particular to cocaine or illegal drugs. Indeed, in announcing his plans, he didn’t blame cocaine for his troubles but “the disease of alcoholism,” which he says led him to make really bad decisions. And alcohol, after all, is perfectly legal.