NYPD cruisers decorated with a political bumper sticker have been cropping up in recent weeks in apparent violation of state law, according to a grassroots group that's been collecting photo evidence since September 20th.

The black, red and white stickers read "VOTE NO! Constitutional Convention = More Taxes," and refer to a once-in-a-blue-moon ballot question in the upcoming November election that could open up the State Constitution to changes.

The Committee for a Constitutional Convention, which is squarely in the "vote yes" camp, issued a press release on the political bumper stickers this week. They say they've counted more than a dozen stickers to date.

"We've been watching it trickle in," said Al Benninghoff, manager of the New York Says Yes Coalition, on Thursday. "But yesterday was a bit of a high water mark when we saw several in the 40th precinct."

"This is a political move straight out of the Tammany Hall playbook," he added in a statement.

Oh look, the NYPD has started editorializing. That's a vote No on ConCon bumper sticker pic.twitter.com/U4niXZa9xg — Nick Rizzo (@nickrizzo) October 12, 2017

Attorney Evan Davis manages the Committee for a Constitutional Convention, and served as counsel to former Governor Mario Cuomo from 1985 to 1990.

"There are clear court of appeals cases that find you may not use public resources, state or local, to promote a 'yes' or 'no' vote on a ballot question," Davis told Gothamist.

Davis also pointed to the gift and loan provisions of the State Constitution, which, he said, "prohibit the use of state money or resources to confer what one person wants."

A Siena College poll back in May found that 67 percent of voters had heard "nothing at all" about the constitutional convention, an obscure opportunity that comes up every 20 years.

But press has been building in recent weeks as the vote approaches, revealing a fissure among Democratic voters.

On one side are the good-government groups, lawyers including the New York State Bar Association, and activists for causes including police reform. These groups acknowledge the risk of cracking open the constitution, but also argue that doing so could allow for sweeping changes that elected officials tend to skirt, like legalizing marijuana, voter reforms, and instating a more stringent environmental bill of rights.

Major labor unions, including the Service Employees International Union and the United Federation of Teachers are on the other side of the debate. These groups argue that the convention could put workers' rights at risk, including the right to workman's compensation.

It's not clear who's responsible for the stickers, though the Patrolmen's Benevolent Association has urged its membership to vote "no," as has the Detectives' Endowment Association (though NYPD detectives don't travel in marked cruisers).

"A Convention may open up New York's Constitution to hastily thought out changes and reversal of laws and protections that in some cases took more than 200 years to put into effect; and for police, benefits that took decades to achieve," wrote Michael J. Palladino, DEA President.

The PBA did not immediately respond to a request for comment.

NYPD vehicle with a political bumper sticker (vote no on the constitutional convention) pic.twitter.com/1ML10jx7az — Liam Quigley (@_elkue) October 3, 2017

Gerald Benjamin is a political science professor at the State University of New York New Paltz. A long time supporter of constitutional conventions, he challenged the factoid on the NYPD bumper stickers that the convention will increase taxes.

"I would say a fair estimate is $70-75 million for the cost of a convention," he told Gothamist. "That's based on applying inflation to the cost of the last convention. The New York budget is $160 billion dollars, so we're talking about... a modest cost."

A constitutional convention could also increase government efficiencies, ultimately reducing government spending, he argued.

As for the risk to employee benefits, Benjamin pointed out that revisions proposed by convention delegates then go to a state-wide vote. "Unions are very strong and people who want to reform government likely won't challenge" their benefits, he said.

"City employees are prohibited from engaging in political activity during work hours, and it is improper for them to use city property for electioneering purposes," City Hall spokesman Austin Finan told Gothamist. "The NYPD is aware of the issue and taking action to ensure the rules are followed."

"The NYPD has directed precinct commanders to ensure that officers are complying with guidelines pertaining to the daily inspection of Department vehicles," Lieutenant John Grimpel added. "These inspections include a visual search for any unauthorized equipment or items affixed to the vehicles."