Opinion

Unfinished business

Just when the Working Families Party thought its legal problems were over comes word that the labor cat’s paw is facing a new criminal investigation.

Frankly, we couldn’t be happier.

Two years after Staten Island DA Dan Donovan formally requested a special prosecutor to look into possible WFP election-law violations, one was finally named.

Turns out the state Office of Court Administration actually made the appointment more than three months ago but didn’t publicly disclose it until last week.

And there’s no explanation as to why it took two full years to get this investigation under way.

But that hardly matters.

The Post first uncovered the WFP’s use of a for-profit subsidiary, Data & Field Services, to skirt campaign-finance rules.

The company provided WFP-endorsed candidates with electioneering services ranging from voter lists to door-to-door canvassing.

In return, the candidates were charged cut-rate prices for those activities — giving them a significant advantage over their opponents and allowing them to skirt legal spending limits.

The WFP, of course, isn’t really a political party at all — it’s a clearinghouse through which elected officials are bought and sold by New York’s public-employee unions.

The operation was especially effective in 2009 — when WFP-backed, hard-left candidates unseated three City Council incumbents and the WFP-DFS machine helped elect Comptroller John Liu and Public Advocate Bill de Blasio.

After a lawsuit filed by former Deputy Mayor Randy Mastro, a state Supreme Court justice ruled that the WFP-DFS arrangement was illegal and ordered the party to shut down the firm.

He also ordered the WFP to pay $100,000 in legal costs to settle the case, after finding the party in contempt of court.

At the time, the WFP expressed happiness that it was finally able to put what it called a “nuisance” behind it.

Guess again.

The newly named investigator, Roger Bennett Adler, has the power to subpoena records and witnesses.

He needs to make the most of it.

And he needs to do so expeditiously.