WASHINGTON _ Former Rhode Island congressman Patrick J. Kennedy, a recovering addict, may seem an unlikely person to spearhead a nationwide campaign to stymie efforts to legalize the recreational use of marijuana.

“I am not the best messenger on this but I am a concerned citizen,’’ the son of the late Massachusetts Senator Edward M. Kennedy and longtime mental health advocate, acknowledged in an interview.

Indeed, even before its scheduled launch on Thursday, a new public advocacy group co-founded by Kennedy is coming under fire from legalization advocates who accuse him of wanting to force pot smokers into treatment.

The Marijuana Policy Project, the leading voice in Washington for legalization, this week called Kennedy’s organization “extremist’’ in circulating a petition urging Kennedy to “drop out’’ of the group and appealing for donations with an image of Kennedy next to the words “Help Us Stop Him.’’


The group accuses Kennedy’s organization of planning to “force marijuana consumers into treatment and marijuana ‘education’ classes.’’

But Kennedy’s group, called Smart Approaches to Marijuana — which is also led by a top pediatrician at Children’s Hospital Boston and a Cambridge-based drug policy expert — is warning of a public health crisis unless a science-based approach is taken to minimizing the harmful consequences of marijuana — especially among youth.

The nonprofit supports making the medicinal properties of marijuana available to patients and is in favor of decriminalizing recreational use and keeping users out of jail. But it asserts marijuana should remain a controlled substance and plans to launch a public education campaign focused on the need to screen users to ensure they are not addicted and at risk of causing long term harm to their mental health.

According to the group’s website, SAM supports an approach “that neither legalizes, nor demonizes, marijuana,’’ while championing “smart policies that decrease marijuana use — and do not harm marijuana users and low-level dealers with arrest records that stigmatize them for life and in ways that make it even harder for them to break free from cycles of substance dependence.’’

Kennedy said the effort was sparked by a series of successful ballot initiatives across the country in November backing legalization of marijuana. Meanwhile, 17 states currently have legislation pending that would make pot legal, including Massachusetts and New Hampshire.


Under federal law, marijuana possession is illegal. But in the aftermath of such support for legalization, federal authorities have said they are reducing enforcement efforts.

“We’ve got bigger fish to fry,’’ President Obama told ABC News last month. “It would not make sense for us to see a top priority as going after recreational users in states that have determined that it’s legal,’’ he added. That reflects a similar approach by federal authorities in the 18 states where medical marijuana is legal. Obama himself smoked marijuana during his youth, according “Obama: The Story,’’ a biography by David Maraniss.

The swiftly changing state laws — marijuana is now fully legal in Washington State and Colorado — concerns Kennedy and other founders of the new group, who believe a public debate about the potential consequences is urgently needed.

“I can’t stand by and let this move forward without any kind of debate or questioning,’’ he said. “This thing could pass right underneath the radar and we will wake up one day and say what were we thinking? I have had a lot of moments like that in my life.’’

He has enlisted Dr. Sharon Levy, a pediatrician and director of the Adolescent Substance Abuse Program at Children’s Hospital Boston.

“There is a lot of messaging from those who support legalization that marijuana is a benign substance,’’ Levy said in an interview. “People are voting on policy but they don’t have the whole story here.’’

She said that, like Kennedy, she is most concerned with the welfare of children and teenagers.


“Marijuana is really bad for your brain,’’ she said, citing depression, anxiety, and cognitive decline. Research also shows it can be addictive for some and trigger psychosis in those genetically predisposed to it.

Levy likened public discourse over pot to tobacco decades ago, when people were told there were no harmful effects to cigarette smoking.

“We have people telling us there is nothing wrong with marijuana. And much like cigarettes back then, you can now find scantily clad women…advertising marijuana. We have been through this before. Like cigarettes, marijuana suppliers’ most profitable customers are adolescents, who are the most vulnerable and will most suffer from long term affects.’’

She, too, believes that pot should be decriminalized but sees a need to keep it illegal, while establishing a screening mechanism and treatment requirements for adolescent abusers, much like there exists for underage drinking.

Kevin Sabet of Cambridge, a former drug policy adviser to President Obama and co-founder of SAM with Kennedy, disputed critics who have charged that the group wants to send marijuana users into treatment.

“We are not forcing anyone into treatment,’’ he said in an interview. “But there should be a public health intervention’’ for users. “We need to watch it so it doesn’t advance, especially if you really want to treat addiction as a disease.’’

The pro-legalization Marijuana Policy Project has also personally attacked Kennedy.

“It is incredibly hypocritical for former Congressman Kennedy to force marijuana users into treatment when his family made money on far more harmful alcohol,’’ said Mason Tvert, communications director for the Marijuana Policy Project. Do they believe every alcohol user should be forced into treatment?’’

Part of the Kennedy fortune that was amassed by his grandfather, Joseph P. Kennedy, came from investments in distillers.

Patrick Kennedy, who retired from Congress in 2010 after his father’s death from brain cancer, has suffered from mental illness and cosponsored legislation that required health insurance companies to treat mental illness in the same way as physical ailments. He has also pushed for new treatment options for substance abusers, drawing on his past addiction to prescription drugs.

Kennedy brushed off the personal attacks being leveled at him.

“I know something about what I am talking about here,’’ he said. “The notion that we want to add any more fuel to the fire flies in the face of all the evidence of an epidemic in this country of epic dimensions when it comes to alcohol and drugs. When are we going to slow this train down instead of adding a new track?’’