AS THE DECADE turns, and I write my last column for the Daily News, I have to shine a light on the most remarkable thing I've seen in 25 years of covering city politics: at last, the appearance of a watchdog that isn't afraid to bite.

I'm talking about the new city Ethics Board, which has been denounced by politicians in City Council and is now being sued by unsuccessful district attorney candidate Dan McCaffery, who blames it for his loss last year.

The pols are squealing because, over the past three years, this aggressive panel has kicked butt and taken names, and in the process changed the way that elections happen in Philadelphia.

They've taken on Council members, congressmen, a sitting judge and the city's most powerful union, and held everyone to a new standard of conduct in Philadelphia political campaigns: obeying the law.

Here's one example. For years, scurrilous attacks on political candidates and public officials have appeared in anonymous fliers, many filled with rumors and half-truths, some appealing to racial or religious prejudice.

The law prohibits anonymous fliers in campaigns, and says that if you spend money producing any campaign material, you have to honestly report that in campaign-expense reports, saying whom you paid to do what.

In the past, when reporters would find out about slimy attack fliers, we'd ask the likely suspects what they knew about it.

We'd get no answers, and since we can't subpoena records or put anybody under oath (and since the previous district attorney had no interest in such trivia), the perpetrators would go their merry way and everyone was encouraged to do the same thing in the next election.

Until the 2007 mayoral primary.

In the closing days of the campaign, two anonymous fliers appeared smearing then-candidate Michael Nutter. One falsely linked him with a 1970s strip-search of African-American men by police. Another, left on windshields at Catholic churches, declared that Nutter was Catholic "when it was convenient for him."

The Ethics Board tracked down the printing broker who'd produced the fliers and asked who'd ordered them. When the broker told the board's investigator to take a hike, the board came back with a court order. Soon the information was flowing.

The trail pointed to two political operatives who appeared to be working for Local 98 of the International Brotherhood of Electrical Workers, which was supporting candidate Tom Knox.

When the Ethics Board asked Local 98's political committee for copies of its expense vouchers for the mayoral campaign, the union's lawyers fought the board all the way to federal court.

The board never quit coming, and in the end the union committee admitted funding the sleazy fliers and paid $10,000 in fines for that and other campaign-reporting violations.

This is just one case that the board has pursued, but I particularly treasure it because I think few things are more corrosive to democracy than the anonymous hit piece.

But you can read about more than a dozen other cases on the board's Web site. In many, politicians simply ignored them, assuming that they'd just go away.

By now, pols have learned that the board doesn't go away, and I think that it's no accident that the hotly contested primaries for district attorney and city controller last year were fairly free of anonymous attack fliers.

The board's executive director, Shane Creamer, has been relentless but fair, enforcing the law and going where the facts lead him, and he's had a board tough enough to back him up. I particularly commend chairman Richard Glazer, who's showed guts and grit in standing up to the city's political power elite.

And credit goes to several lawyers who've done pro bono work for the board, notably Cheryl Krause, who handled the Local 98 case.

The board has gone after traditional machine politicians like U.S. Rep. Bob Brady and the late ward leader Carol Campbell, and darlings of the liberal community like Councilwoman Maria Quinones-Sanchez and District Attorney Seth Williams.

Anyone who cares about the progress that the board has made will be closely watching the suit McCaffery has filed. Having read his complaint and the board's response, it seems to me that it should be quickly dismissed.

So, as I leave the Daily News to work for WHYY, the city's public-broadcasting station, I say God bless the new ethics posse in town. If they keep this up, we may finally shed our "corrupt and contented" tag.

Finally, this update on a column I wrote in November: Denise Bentley, the city prison guard who'd been repeatedly suspended because of assault and terroristic threat accusations from her ex-husband, is back on the job.

The District Attorney's Office declined to prosecute the latest case against her.