The new law legalizing marijuana for medical use will generate more car crashes here and require more police training and court time, Westborough Police Chief Alan Gordon told the planning board Tuesday night.

Gordon does not support trying to ban the medical use of marijuana outright, though.

“I think that an outright ban is going to get challenged. And I’m not real confident it’s going to withstand the challenge to the attorney general’s office,” Gordon explained.

The planning board convened Tuesday night’s meeting with town officials to discuss Westborough’s response to the new law, which takes effect Jan. 1.

The board directed Town Planner Jim Robbins to draft a zoning bylaw for discussion starting at the board’s Dec. 13 meeting.

The board plans to hold a public hearing on the proposal in early 2013 and then seek town meeting approval in March .

The efforts would be in case the state Department of Public Health hasn’t implemented regulations before the law takes effect Jan. 1, town officials said.

Anyone wishing to open a dispensary or to cultivate marijuana for medical use would have to wait until town meeting voted and for Attorney General Martha Coakley to rule on its legality. The advertisement date starts the clock.

“I’m definitely in favor of setting up such strict guidelines as far as the zoning so that it makes it less attractive to somebody that wants to come in. If they look at some other community that hasn’t been as proactive as you people are now, they may look at that as a place to target,” Gordon said.

The new law will be “a major issue for us,” he said.

“Basically, when they decriminalized marijuana, kids viewed it as legalizing marijuana. And the law does not have any teeth to it,” Gordon said. Police can issue a $100 civil citation for possession of under an ounce, he noted.

“It’s going to be difficult. I can envision a lot more driving under the influence cases, which is a problem because we have no machines that detect somebody that’s driving under the influence of narcotics,” Gordon said.

Police will require more officers certified as drug recognition experts for use at such scenes as operating under the influence crashes, he said.

“Obviously, the law is going to allow them to have it for medicinal purposes. But, the law in regards to operating under the influence is still going to stand,” Gordon said.

“Each department may have one (expert). You’re probably going to have to have everybody certified.”

The training, and court time, will cost municipalities money, Gordon said.

“It’s going to have a trickle-down effect, and it’s going to effect every one of our budgets,” he said.