Candidates who place campaign advertisements on lampposts, bus shelters, and other public street fixtures could face stiff fines from the Sanitation Department, according to a letter sent last month to all office seekers by the department’s commissioner, John Doherty.

The city’s Poster Law imposes a penalty of between $75 and $150 for the first piece of printed material that is affixed to public property, and of up to $250 for each additional violation, according to Mr. Doherty’s letter, which was mailed July 28.

But the department has yet to enforce the regulation during this campaign season, according to a Sanitation spokesman, Keith Mellis. He said the department did not levy a single fine for that violation during the 2004 campaign either.

Mr. Mellis said the candidates “just got the letter, so we have to give them a chance.”

“If you have handbills all over the place,” he said, “it takes you a while to take them all down.”

Asked when the Sanitation Department would begin to slap fines on Poster Law violators this year, Mr. Mellis said, “I can’t give you a date.”

A constitutional lawyer who is running for public advocate, Norman Siegel, said he is “very frustrated” by the strict Poster Law – and its lax enforcement.

Mr. Siegel said he abides by the law, and has been keeping track of violators. While marching along Grand Concourse in the Bronx Puerto Rican Day parade on Sunday, he noted that one lamppost featured 10 signs for Mayor Bloomberg’s re-election bid.

A Bloomberg campaign spokesman, Stuart Loeser, acknowledged that the mayor’s supporters had posted signs along the historic Bronx boulevard before the march, but he said the campaign removed all the signs after the parade.

The city’s Poster Law does not contain an exception for posters in place only temporarily. All advertisements on public property are barred.

Walking past a museum-scale collection of handbills on Eastern Parkway in Crown Heights last week, a neurologist, Joyce Ilson, said she was not bothered by the ubiquitous campaign posters.

“It’s letting you know what the choices are,” Dr. Ilson said. “Some laws shouldn’t be enforced because they shouldn’t be laws in the first place.”

A spokeswoman for the Sanitation Department, Kathy Dawkins, said, however, that illegal posters “cause litter and dirty streets.”

Mr. Siegel said “there should be a First Amendment right to have posters up for campaigns.” But a Los Angeles municipal ordinance similar to New York’s Poster Law withstood a constitutional challenge more than two decades ago.

In the 1984 case of City Council of Los Angeles v. Taxpayers for Vincent, Justice Stevens, in a majority opinion joined by five other members of the Supreme Court, wrote, “the visual assault on the citizens of Los Angeles presented by an accumulation of signs posted on public property constitutes a significant substantive evil within the City’s power to prohibit.”

“I think that case was wrongly decided,” Mr. Siegel said.

He proposed a compromise measure under which Sanitation would allow campaign posters on public property in the 10 days before an election. Under Mr. Siegel’s proposal, candidates would have to remove the posters within three days after Election Day.

Mr. Siegel said he has urged City Council members, including the speaker, Gifford Miller, to introduce the proposal, to no avail.

An earlier version of the city’s Poster Law was struck down by the Appellate Division of the state Supreme Court in 1991. That ruling came in response to a challenge by a music promoter, Robert Sulzer, whose stage names, Bad Newz and Bob Z, appeared on handbills affixed to lampposts in Manhattan and Brooklyn. The city imposed $2,900 in fines on Mr. Sulzer in 1988, even though it could not prove that Mr. Sulzer himself was responsible for the illegal handbills.

Since that ruling, the city has altered the language of its law to reflect the appellate court’s decision, according to the legal director of the New York Civil Liberties Union, Arthur Eisenberg, who served as one of Mr. Sulzer’s attorneys. The law now contains a “rebuttable presumption” that the person whose name appears on an illegally posted handbill is responsible for its placement.