The Democratic Party is at its best when it stands up for children's well-being. It's at its worst when its libertarian impulses trump that vital value. (That's true of the Republican Party, too.)

Former Gov. Mark Dayton admirably stood up for children's well-being by opposing the libertarian impulse to legalize recreational marijuana. Dr. Ed Ehlinger, Dayton's former commissioner of health, spoke out on the dangers of pot on these pages ("For medical use? Yes. Open adult use? Not yet," Feb. 28) and in legislative testimony, swinging key votes against legalization.

The legalization movement now has reasserted itself, though not in exactly the context it might have wished. An article on a recent Star Tribune front page was headlined "DFL to make its case for legal pot" (Aug. 30). Page A2 of the same issue headlined a U.S. surgeon general's warning about the harmful effects of marijuana on the adolescent brain. (The article noted that the American Medical Association "strongly supports" this federal warning effort.)

Here are some excerpts from the surgeon general's report: "Frequent marijuana use during adolescence is associated with changes in the areas of the brain involved in attention, memory, decision-making, and motivation. … Chronic use is linked to declines in IQ, school performance that jeopardizes professional and social achievements, and life satisfaction. … Marijuana use is also linked to risk for and early onset of psychotic disorders, such as schizophrenia."

Minnesotans should be well aware of marijuana's correlation with poor school performance. A Star Tribune article on Feb. 21 described a University of Minnesota study of some 10,000 college students. It found a clear association between marijuana use and lower grades.

At about the same time, Alex Berenson published "Tell Your Children: The Truth About Marijuana, Mental Illness, and Violence." Berenson is a former New York Times investigative journalist. He personally had used pot and "tended to be a libertarian on drugs," until his wife (a Harvard-trained psychiatrist) alerted him to the link between marijuana and psychosis.

Berenson marshals evidence linking marijuana to increased risks of schizophrenia and paranoia. He cites dramatically increased psychotic emergency room admissions, as well as increased rates of violent crime, as states legalize recreational pot.

Meanwhile, in Britain, Berenson says, something entirely different has happened. The public moved from supporting legalized pot to opposing it, and rates of marijuana use declined. The reason is that British psychiatrists spoke out forcefully about the link between pot and mental illness.

American psychiatrists have been drowned out by promotional campaigns. Berenson deplores "a long, expensive, and shrewd lobbying effort that has been funded largely by a handful of the world's richest people." One billionaire has donated more than $100 million to legalizing pot.

Legalization signals social approval to teenagers. Opening dispensaries with jubilation and fanfare signals that cannabis is safe, and it encourages teenage use, notwithstanding all sorts of windy warnings. As Berenson says, "legalizing marijuana, especially in its current high-THC form, amounts to running a giant real-time experiment on the brains of adolescents and young adults."

The ultimate argument that legalizers always stress is that of racial disparities in enforcement. As Berenson states, however, the civil-rights issues "are far more complicated than the media or politicians would like them to be."

We're striving to close egregious racial gaps in academic achievement. What sense does it make to legitimize something that disrupts teenage brain development, that impairs motivation, cognition, learning and memory, and that correlates with low grades? Low-income households have higher rates of marijuana use, and teens in those households are often acutely exposed.

Civil-rights concerns can be met with restrained enforcement and lighter penalties. Possession of small amounts of pot can be dealt with by ticketing, with no arrest record if fines are paid. But legalization is bad policy, and it should be firmly resisted.

The Republican Party has plenty of faults, but on this issue it's acting commendably. It's taking a large political risk with an anti-libertarian stance against slick libertarian marketing in a libertarian era. It's taking a scientifically grounded position supporting children's well-being.

There's nothing "progressive" about legalizing recreational pot. It diminishes people, and it irrefutably endangers teens. We need principled Democrats like Mark Dayton with the moral courage to stand up against the libertarian blitz and oppose the pot-legalization campaign.

John Hagen, of Minneapolis, is an attorney.