File--In this Friday, Dec.18, 2015, file photograph, the logo is shown on the front of jars of marijuana buds marketed by rapper Snopp Dogg in one of the LivWell marijuana chain's outlets south of downtown Denver. As legal marijuana becomes a further-entrenched fact of life in Colorado, small-town leaders are struggling to sort out the same issues that Denver and other cities have tangled with, from zoning for grows and dispensaries to allowing cannabis clubs. (AP Photo/David Zalubowski, file)
File--In this Friday, Dec.18, 2015, file photograph, the logo is shown on the front of jars of marijuana buds marketed by rapper Snopp Dogg in one of the LivWell marijuana chain's outlets south of downtown Denver. As legal marijuana becomes a further-entrenched fact of life in Colorado, small-town leaders are struggling to sort out the same issues that Denver and other cities have tangled with, from zoning for grows and dispensaries to allowing cannabis clubs. (AP Photo/David Zalubowski, file) Credit: David Zalubowski—AP

The battle lines have been drawn over legalizing marijuana for recreational use here in Massachusetts.

A recent poll shows the public is pretty evenly split on the issue. Forty-six percent of respondents in a Suffolk University/Boston Globe poll earlier this month were against legalizing the drug for recreational use and 43 percent supported legalization. With six months to go before voters give their final answer in a referendum, they and state officials should consider several concerns — potency, driver impairment and the black market — that are starting to get attention.

We think these issues should give everyone pause, regardless of where they stand on the issue. And it’s why we back state Senate President Stanley Rosenberg’s effort to get the Legislature and Gov. Charlie Baker to pay attention to the potential downsides of legalization.

As Rosenberg explained in a recent interview, “once the voters vote a question in, the proponents fight tooth and nail to ensure it is not undermined in intent, and they often fight to maintain it in most or all its detail. So we’re going to have quite a time if the ballot question passes and we (lawmakers) come in and try to fix it.”

Instead, he would have the Legislature and governor propose the fixes in advance through their own ballot question — one formed by study, debate and compromise by all interest groups, not just legalization proponents.

It’s a significant concern for Rosenberg, given the research the Senate has conducted into what’s happening in the states such as Colorado or Washington that have legalized recreational marijuana use. 

The sale of marijuana for recreational use hasn’t ended the black market. States are still seeing illegal marijuana brought from elsewhere and sold on their streets while the legal product is being smuggled out of state, a Senate group learned. Nebraska and Oklahoma have filed lawsuits because they say their jails are filling up with people smuggling pot from neighboring Colorado.

Law enforcement officials say potent edible forms of pot, containing high amounts of its active ingredient, THC, are leaving Colorado. It’s the hidden potency of drinks, cookies, candies, etc., that worries Rosenberg.

“The fact that people can access it who shouldn’t … if someone forgets and leaves the gummy bears on the table, and then Johnny comes along and grabs a snack … but these aren’t your ordinary gummy bears,” the Senate president said.

Even adults can fail to take into account digestion time and therefore eat more than they should, leading to higher levels of intoxication.

That’s risky, particularly for someone getting behind the wheel of a vehicle. The percentage of drivers involved in fatal crashes who had traces of THC in their blood has doubled since marijuana was legalized in Washington state, a study by the AAA Foundation for Traffic Safety has found.

Meanwhile, law enforcement and state governments are also finding they can’t measure the impairment of pot-smoking drivers in the same way they do drunken drivers.

“There is understandably a strong desire by both lawmakers and the public to create legal limits for marijuana impairment, in the same manner as we do with alcohol,” said AAA chief Marshall Doney. “In the case of marijuana, this approach is flawed and not supported by scientific research. It’s simply not possible today to determine whether a driver is impaired based solely on the amount of the drug in their body.”

Rosenberg is right in wanting to have the state put more thought into the question and exert more control. “You really should have the kind of deliberative process that a Legislature engages in to come up with best answers, rather than having people reinforcing each others’ beliefs,” he said.

The House and the governor would be wise to think along the same lines. Better to be thorough now than sorry later.