This may be the worst mainstream media article in some time.
Rita Rubin vomits a piece in USA TODAY today: CAUTION: Marijuana may not be lesser evil —
‘Gateway drug’ or not, experts say, it’s not a benign path for teens
It’s a big steaming pile of poor journalism, including the standard anecdotal “evidence”

By the time Gardner was a junior, he started skipping high school regularly to smoke pot. “I would always find somebody who wasn’t at school that day and get high with them,” he says. Gardner says he missed 50 days in the first semester of his senior year. His parents discovered his stash of marijuana and sent him to a psychiatrist. His grades plummeted; his college plans evaporated.

or…

Rachel Kinsey says drug addiction runs in her mother’s family, although not in her immediate family. Kinsey, 24, started drinking alcohol at 14 and smoking marijuana at 15 Ö “definitely a predecessor for everything else I used.” She began using Ecstasy and cocaine at 17, then heroin at 18.

But the article headline also promised experts, right?

Adolescents have the greatest rates of marijuana use, and they also have the greatest amount to lose by using marijuana, scientists say.

Ah, good. Scientists. Here we go…

“Adolescence is about risk-taking, experimentation,” says Yasmin Hurd, professor of psychiatry, pharmacology and biological chemistry at the Mount Sinai School of Medicine in New York who published a rat study last summer that found early exposure to THC, the psychoactive ingredient in marijuana, led to a greater sensitivity to heroin in adulthood.

Wait a second. Yasmin Hurd? Rat study? Oh, yeah. That would be this nonsense and as it turns out actually appeared to prove that of those rats who were forced to use heroin, those who hadn’t previously been pre-treated with THC were more likely to become heavily addicted to heroin. (At least to the extent that you can draw any relevant conclusions out of a situation involving THC-pre-treated rats who are due to be decapitated.)
And, of course, the thing we know for certain about the gateway theory:

Over 99% of those who never try marijuana will not become addicted to heroin.
Over 99% of those who do try marijuana will not become addicted to heroin.

Update: Jacob Sullum has a more charitable description of Rita Rubin’s journalism, claiming that she is trying to undermine her paper’s propaganda. I suppose that’s possible, but it looks more to me like a half-assed attempt to show “balance” in a piece that’s clearly written with an anti-marijuana agenda.