An activist associated with the group Boulder County Protectors was cited by police Tuesday night for projecting the image of a skull and crossbones along with the words “Ban Fracking!” onto the exterior wall of the old courthouse off the Pearl Street Mall.

Boulder County Attorney Ben Pearlman, who police said directed them to issue the trespassing ticket, said the image and phrase violated the county’s building-use policy. But a legal expert with the American Civil Liberties Union said the man was within his constitutional rights.

“I think that it looks like this ticket was issued in retaliation for exercising his First Amendment rights,” said Mark Silverstein, ACLU of Colorado’s legal director.

Members of Boulder County Protectors, the group that hung an anti-fracking banner on the Flatirons last month, were protesting outside the Boulder Theater, 2032 14th St., during Boulder’s celebration of the 50th anniversary of the city’s open space program.

The activists, some clad in hazmat suits, handed out information and served a green punch they called “fracking fluid” in an effort to educate the public about what they say is an imminent threat of oil and gas development on publicly owned open space land.

David Paul, 54, said he had set up his light projector in a friend’s truck outside the theater. He shone the image of a red skull and crossbones and the phrase “Ban Fracking!” onto the Boulder County Courthouse East Annex, across the street from the theater, at 2045 13th St.

Boulder police issued Paul a citation for trespassing around 8:30 p.m. Tuesday, spokeswoman Laurie Ogden confirmed.

“It was issued at the direction of Mr. Pearlman,” Ogden said.

In addition to the Flatirons display, activists with Boulder County Protectors have been known to project anti-fracking messages on public buildings.

“Occasionally, we will notice that they’ve shined a light somewhere, but if we’re not there to notice it, then it’s difficult to enforce it,” Pearlman said Wednesday. “The policy is very clear and we would treat any instance, regardless of the group, the same way.”

This time, Pearlman happened to be in attendance of the anniversary party, where he witnessed the projection onto the side of the courthouse building.

He said the content of the message projected onto the wall was irrelevant to the decision to seek a police citation.

“This is the county building and the county does not want swastikas or any other messages that they don’t want on those walls,” Pearlman said.

He said the county does not allow images or phrases — political or otherwise — to be beamed onto the building, and the courthouse’s front lawn is the only place people can publicly gather to protest.

Pearlman added that he would only seek a citation if the person using such a light projector refused to turn off the image, as happened Tuesday night.

The county’s policy, in part, states that, “Signs, banners, lights or other materials affixed to or projected against the walls or surfaces of county-owned buildings and structures other than those owned approved by the (Board of County Commissioners) or another Elected Official are prohibited.”

But the Boulder trespass ordinance that Paul is accused of violating states that no person shall: “Enter or remain upon land or premises other than a dwelling of another in defiance of a legal request or order by the owner or some other authorized person.” The ordinance also states that no person shall enter land or a building that is locked, fenced or enclosed by the owner in order to keep people out.

Paul said he was standing on public property the entire time he was there and doesn’t believe he broke the law. He has not received citations for other light displays.

Amelia Arvesen: 303-684-5212, arvesena@times-call.com or twitter.com/ameliaarvesen