Professor Robert Ovetz was driving through San Francisco on the morning of June 30 when he saw the lights of a police car behind him.

Ovetz pulled over.

"When the officer came up to my window, he asked the typical police requests: registration, drivers’ license, insurance card," says Ovetz. "I asked him why he was pulling me over. And he said because of the bumper sticker on my back window."

That sticker says, "No to Empire," in large bold letters, and on the bottom in very small letters, "www.thenation.com," Ovetz notes. It’s a bumper sticker from The Nation magazine.

Ovetz’s first reaction was to laugh, he says.

Then he recalls the following conversation:

"How could it be illegal for me to have a bumper sticker on my back windshield?"

"It’s obscuring your view."

"You’re just trampling on my free speech rights."

"No sir, I’m just doing my job."

At that point, the officer went back to his squad car for a few minutes.

When he returned, he gave Ovetz a ticket.

That ticket cited part of the vehicle code that prohibits driving a car if the "driver’s clear vision" is "obstructed by snow or ice" on the car windows.

"I’ve never seen snow in June in San Francisco," says Ovetz’s attorney, Ross Dreyer.

The code also says, "No person shall drive any motor vehicle with any object or material placed, displayed, installed, affixed, or applied upon the windshield or side or rear windows."

While this would seem to apply to Ovetz, it also would apply to anyone who puts a college decal on their windshield or their high school athletic team’s name or anything else, for that matter, including stickers endorsing candidates.

The officer’s name is Mike Mitchell (Star number 4160), according to Ovetz, who notified him that he would be publicizing this incident.

"I asked to get the spelling of his name and told him I’ll be doing a press release on this," Ovetz said. "And I asked him, "What if the sticker had said, Yes to Empire, would you have still ticketed me?’ "

According to Ovetz, Officer Mitchell responded: "I don’t care if you’re a Star Wars fan, or not."

Ovetz responded: "You know, clearly you’re just harassing me because of what it says."

The officer remained polite, Ovetz says, and told him that if he removed the sticker, he could go to court and the ticket would be dismissed, possibly with a small fine.

"And I said, ‘I’m not removing the sticker.’ That was pretty much it."

Ovetz believes he was a victim of "selective enforcement because of his political message and the policeman’s own bias."

A lot of other cars have "a spare tire, or another sticker, or a bicycle car rack" that could be cited for obstructing the view, he says.

"We’re filing a petition to the court to have the charges dropped," he says. Ovetz, a professor of political science and sociology at the College of Marin and Cañada College, bemoans the state of our civil liberties. "We can’t even speak about the implication of empire in our country," he says. In his press release, he added: "It is disturbing that in one of the most liberal cities in America, citizens cannot freely express their opinions without fear of government harassment and intimidation."

Sergeant Wilfred Williams is a public information officer at the San Francisco Police Department.

"He can protest the ticket," says Sergeant Williams, who offers "no comment in regards to the officer doing his job."