The Vermont House on Thursday gave final approval to a bill that would create a legalized retail marijuana market, but not before amending it to ban virtually all weed-related advertising.

Rep. Anne Donahue (R-Northfield), who proposed the amendment, told her colleagues on the House floor that allowing cannabis advertisements goes against what she believes is the bill's main intent.

"The purpose of the bill is safety for current users," Donahue said. "If there are more people who start using because they see ads, that means there are more people potentially on the highway driving impaired; there are more children exposed — the negative things that we don't want to see happening."

While she acknowledged First Amendment concerns, Donahue said that courts in two other states have landed on different sides of the issue. That convinced her that it's worth a try in Vermont, she said.

"I think we have a compelling [state] interest here," she said.

Donahue's argument seemed to convince her colleagues, who unanimously passed the amendment during Thursday's floor debate. Lawmakers later shot down another last-minute proposal that would have allowed for roadside saliva testing before they passed the bill a final time.

Donahue's amendment would allow some limited advertising — labels on products, educational material and signs attached to buildings — while banning all other forms.

That's a big change from the initial proposal, which did include strict standards. Under those proposed rules, media whose audience was more than 15 percent youth could not run cannabis ads. The yet-to-be-created Cannabis Control Board would be empowered to preapprove all ads prior to dissemination.

House Government Operations Committee chair Sarah Copeland Hanzas (D-Bradford) told Seven Days that her committee, which wrote those rules, intended the most stringent restrictions that could "pass constitutional muster."

But after Donahue's pitch, the group favored stronger restrictions, Copeland Hanzas said, which is why members unanimously backed her proposal.

Rep. John Gannon (D-Wilmington), vice chair of Gov Ops, agreed that the ban jibes with the bill's intent. "We really were focused on making sure that children were not going to be encouraged to use cannabis in the bill," Gannon said. "I think this will help."

Not everyone agrees.

Dave Silberman, a Middlebury attorney and pro bono cannabis advocate, said the public would have been better protected under the House's initial rules, because the ban would likely be shot down in court.

"It's an unforced error," Silberman said.

Still, Silberman didn't seem too concerned. He noted that the advertising issue is among many differences between the House and Senate versions of the bill, and said that he believes the change will be dropped in a conference committee that must reconcile the versions.

One lawmaker who will influence those decisions is Sen. Dick Sears (D-Bennington), one of the bill's sponsors.

Sears hadn't heard about the amendment when asked Thursday afternoon, so he was hesitant to take a firm stance without reviewing the details. But he noted that the Senate Judiciary Committee, which he chairs, considered potential advertising restrictions and decided that a flat-out ban would violate the First Amendment.