Supporters of legalizing marijuana were put on the defensive Wednesday by almost two hours of testimony offered by Dr. Deepak Cyril D’Souza, a professor of psychiatry at Yale University School of Medicine and director of neuropsychiatry at the VA Connecticut Healthcare System.

D’Souza told the legislature’s Judiciary Committee that marijuana is addictive and research has shown that about 10 percent of people who try marijuana will become addicted.

He said it’s not as addictive as opioids or cocaine, but it is addictive and there are withdrawal symptoms.

He said there’s an increase in the demand for treatment of marijuana addiction as more people become addicted to cannabis, but “there’s nothing for us to offer them,” in the form of treatment. D’Souza said unlike with opioids or cocaine there’s no proven way to treat someone for an addiction to marijuana.

D’Souza said over the past 20 years he’s been studying this issue and doing research, “I don’t see any people performing better under the influence of cannabis.”

He said researchers have found that the “more marijuana you smoke the greater your likelihood of a number of cognitive deficits.” And exposure in adolescence was related to “significant reduction in IQ,” D’Souza said.

A longitudinal study found that those cognitive deficits persisted, D’Souza added.

But for proponents of the legislation, which is one of four bills this year calling for legalization, cannabis provides a safer alternative to opioids and many maintained it’s a less harmful drug than alcohol. For other supporters it’s about addressing the impact that marijuana prohibition has had on society, specifically minority populations, and raising revenue for the state.

“Marijuana prohibition has lasted 80 years,” Senate President Martin Looney, D-New Haven, said in written testimony. “Yet, it has been just as much of a failure as America’s short-lived experiment with alcohol prohibition. It is time we take the same rational, common-sense approach to marijuana, as we did with alcohol: regulating and taxing it.”

The bill proposed by Looney proposes a structure for taxation of marijuana and marijuana products inspired by the approach Colorado has taken. Looney’s legislation would impose a special 23.65 percent sales tax on all marijuana and marijuana products at retail. The special sales tax would be in addition to the regular 6.35 percent sales tax and would amount to a combined effective sales tax of 30 percent.

Maine and Massachusetts voters approved ballot initiatives this past November and are expected to open up stores next year. Rhode Island, Vermont, and New Jersey legislatures are all considering enacting similar measures, Looney said.

A March 11, 2015 poll by Quinnipiac University found that 63 percent of Connecticut voters support the legalization of marijuana.

Looney citing a report by the Cato Institute, a free market think-tank, said the group’s 2016 report found “state marijuana legalizations have had minimal effect on marijuana use and related outcomes.”

The report also found that available data from Colorado and Alaska on marijuana use from the Youth Risk Behavior Survey showed no obvious effect of legalization on youth marijuana use.

Rep. Toni Walker, D-New Haven, said when minority kids do normal adolescent things like experimenting with drugs that sometimes the circumstances lead to incarceration.

“By making it a criminal offense it pushes more kids into a system that will not allow them to have another chance,” Walker said.

Connecticut decriminalized possession of less than a half ounce of marijuana in 2011.

“We are not incarcerating individuals who are using marijuana for personal use,” Rep. Rosa Rebimbas, R-Naugatuck, said. “It’s still illegal to deal in marijuana.”

Walker said kids in her community are in prison because of this and “this is the number one issue they’re having.”

She said when she looks at the juvenile justice system the kids look more like her and there is a “definite disproportionate contact,” with her community, which is why she’s in favor of legalization.

But that doesn’t mean she condones the use of marijuana for children.

“I think we need to spend more time educating our children about the harmful uses of all of these things,” Walker said.

Becky Dansky, legal counsel for the Marijuana Policy Project, said research shows that there has not been an increase in teen cannabis use in states that have legalized marijuana.

She said there are eight states and Washington D.C. which have legalized marijuana, but Colorado often gets mentioned as an example because it was the first. She said teens in Colorado used marijuana at a higher rate than teens in other parts of the country before legalization.

Rep. Vincent Candelora, R-North Branford, said he worries that legalizing marijuana gives teens the impression that smoking marijuana is safe.

Dansky said the legislation is only seeking to legalize marijuana for adults 21 years and older.

She said they endorse child-proof packaging.

“This is not something for children. This is a product for adults,” Dansky said.