The bipartisan 118-page analysis comes the same week Governor Charlie Baker, Attorney General Maura Healey, and Mayor Martin J. Walsh of Boston published a sharply worded opinion column in The Boston Globe opposing legalization, and the Legislature’s judiciary committee heard testimony on the ballot push.

The report by a special Senate committee does not take an official stance on the proposed ballot question but warns of legalization’s dangers. The authors note that it could make it easier for children to access the drug and create difficulties for law enforcement officers in determining and proving someone is too high to drive.

A scathing Senate report to be released Tuesday says that if residents legalize recreational marijuana in Massachusetts this fall, the state should promptly temper their vote by outlawing home cultivation, imposing a significant tax on the drug, and prohibiting some marijuana-infused edible products.


Taken together, the analysis and the opinion column offer the clearest outline yet of the messages legalization opponents may use and give voters a taste of the debate that could unfold across the state.

Senator Jason M. Lewis, a Winchester Democrat and chairman of the Special Senate Committee on Marijuana, said the nine-member committee’s conclusions include “serious concerns about the prospect of legalizing marijuana for recreational use and sale in Massachusetts.”

The proposed law from the Campaign to Regulate Marijuana Like Alcohol in Massachusetts would legalize recreational marijuana use for those 21 and older. Proponents say they aim to create a regulated and taxed market, removing marijuana sales from the criminal sphere.

The law, if approved by voters, would set a January 2018 deadline to commence recreational retail sales. It would create a “Cannabis Control Commission,” with members appointed by the state treasurer to oversee a system of marijuana stores, cultivating facilities, and manufacturers of edible products. It would allow adults to grow up to 12 marijuana plants for personal use per household.


The proposal, backed by the national Marijuana Policy Project, would impose a 3.75 percent excise tax on retail marijuana sales, in addition to the state’s 6.25 percent sales tax — and it would also allow cities and towns to levy an additional 2 percent tax that the municipalities could keep.

Legislative leaders have repeatedly said lawmakers don’t have the wherewithal to approve a bill legalizing marijuana themselves. But because the pro-legalization group is expected to collect sufficient signatures to put the issue directly before voters, legislators have spent the past year studying the issue and preparing to respond to the referendum.

Lewis said the intent of the committee — which interviewed about 75 experts and visited Colorado, which allows recreational sales, for almost a week — was to anticipate the issues the state would face and create a comprehensive set of recommendations to implement should voters legalize marijuana on their own.

He said the big-picture goals are common sense: preventing marijuana use by people under 21, minimizing adult addiction and black-market sales, ensuring a well-regulated marketplace, and making sure the marijuana revenue covers the costs of regulating the new industry and public education measures.

The report presses for action in areas the ballot question does not directly address. Among others: setting a legal driving limit for blood levels of THC, the primary psychoactive substance in marijuana; mandating that marijuana advertising and product labels warn of health risks; gathering data on marijuana issues to measure trends; determining how to operate a legal market when marijuana remains illegal on the federal level; and raising the legal sales age for tobacco from 18 to 21 “so there is a consistent legal age for alcohol, tobacco and marijuana.”


The report also argues that many of the ballot question’s provisions are insufficient and calls for changes. Because the initiative petition, if approved by voters, would simply create a new law, the Legislature could amend it like any other statute.

While the ballot measure calls for people to be able to legally grow up to 12 marijuana plants per household, the committee suggests Massachusetts prohibit all home growing or, at least, impose a temporary moratorium.

The senators noted that home-grown marijuana would not be tested for safety or potency and would not be subject to the tracking requirements of commercially grown plants. Furthermore, it would be extremely difficult to police and could lead to diversion of marijuana to the black market, along with a host of other potential troubles.

“What about if it’s a multi-family residence?” Lewis asked. “Now you’ve got other people living there that may have to deal with the odor. You have issues with children in the household if you’re growing marijuana.”

While the ballot would set the recreational marijuana tax rate, including the state sales tax, at no more than 12 percent, the report says the total tax should be set much higher, perhaps three times as high.


That’s because, according to the committee, the state revenue raised by the lower tax rate would not cover the associated direct costs of legalization, such as regulating businesses and educating the public. But a push for a high tax rate is sure to raise concerns that the black market would flourish even after legalization.

If marijuana were legalized, the report recommends that Massachusetts prohibit the manufacture and sale of marijuana products that are “particularly appealing to youth and may be mistakenly consumed by children.”

That’s a response to instances of accidental consumption of marijuana-infused foods by kids and overconsumption by adults, both of which have landed people in the hospital in stateswhere the drug is legal.

But the prohibition could effectively gut a big part of the market. Edibles constitute nearly half the legal market and are its fastest-growing segment, the report found.

Many of those edibles — including products such as sour gummies and chocolate chip cookies — could reasonably be described as “particularly appealing to youth” and all could, outside of their packaging, be mistakenly consumed by children.

Lewis said the recommendation is not intended to be a poison pill for legalization; rather the committee is trying to have “reasonable limits on the kinds of products that can be on the market.”

Although the report was not yet public Monday, the group pressing legalization in Massachusetts, the Campaign to Regulate Marijuana Like Alcohol, offered something of a pre-buttal.

“It appears some committee members traveled to Colorado with a bias against regulating marijuana” said spokesman Jim Borghesani, “and sought information to buttress their positions.”


Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos .