It’s good news that the Sanitation Department is finally enforcing a law banning campaign literature being posted on city-owned property, despite the undesirability of the law in the first place. By our lights the law is against political speech and its repeal would be welcome. But as long as a law remains on the books it’s the responsibility of city officials to enforce it.

Candidates have been fully aware of the poster law. As The New York Sun reported last month, Commissioner John Doherty reminded office-seekers in a July 28 letter of the law and of the penalties for violations: Between $75 and $150 for the first piece of printed material and $250 for each subsequent violation. Yet as campaigning began illegal posters went up, and the department did nothing. At a meeting with The New York Sun last month, a candidate for public advocate, Norman Siegel, said he was “very frustrating” by other candidates “a clear violation of the rule of law.”

The department is now finally enforcing the law. The New York Times reported yesterday that nearly 5,000 illegally placed posters have now been taken down. In the mayoral race the worst offender was the former president of the Bronx, Fernando Ferrer. Between August 10 and 31, according to the Times, Mr. Ferrer had 194 illegal campaign posters removed. Mayor Bloomberg meanwhile had 138 removed, and the president of Manhattan, C. Virginia Fields, had 132. Better behaved, but law-breakers nonetheless, were: the speaker of the City Council, Gifford Miller, with 28, and Rep. Anthony Weiner with four. Of all office-seekers the worst law-breaker was state Senator John Sampson, who is running for district attorney in Brooklyn. He had 1,184 illegal posters taken down. And he wants to fill a position charged with enforcing laws.