In the name of cleaning up elections from “special interests,” Mayor Bloomberg and the City Council are about to hand a political advantage to one of the most powerful special interests in the city, labor unions. The deal between the mayor and the council announced yesterday would totally ban contributions from limited liability companies and limited liability partnerships, common ways for businesses to organize themselves. Yet it does nothing to ban campaign contributions from labor unions. Further restrictions apply to businesses and individuals that have contracts for more than $100,000 with the city, but, as our Jill Gardiner reports at page one, it wouldn’t apply to unions, such as the United Federation of Teachers or District Council 37 of the American Federation of State, County, and Municipal Employees, that have contracts worth billions of dollars a year.

The City Council speaker, Christine Quinn, hailed the new restrictions as “limiting the influence of big business.” The idea that “big business” has too much influence in a city where the council has celebrated its success in keeping the nation’s largest retailer, Wal-Mart, out of the municipal boundaries is beyond laughable. If it were up to “big business,” it’s unlikely that New York would have the highest combined state and local tax burden in the nation, the proceeds of which are used to fund one of the largest and most lavishly compensated public-employee workforces in the world.

The same day the council announced it was “limiting the influence of big business,” the City Council overrode the mayor’s veto to pass a “whistleblower protection law” drafted by the United Federation of Teachers that amounts to a bad-teacher protection act. Yesterday’s campaign finance deal would have First Amendment problems even if it did include unions, and we doubt that in this form it will survive a court challenge on either free speech or equal protection grounds. These columns oppose restrictions on contributions by either business or labor, preferring contested elections and judicious criminal enforcement of antibribery laws as a way of keeping politicians honest. Tax cuts so that the politicians would have less money to ladle out at their discretion would also help. But if there are to be restrictions on contributions, at least they should apply equally to business and to labor.

If such an imbalanced deal on campaign finance is allowed to become law, it could leave Mr. Bloomberg’s successor with a problem even worse than the budget gaps Mr. Bloomberg recently complained that he was left when he entered office. The legacy left by Mr. Bloomberg — which includes so much that is good in this city, including a newly minted AA bond rating — would be tarnished by a system of campaign finance rules in the city that is tilted toward labor and against business. This mayor is a businessman with a reputation for integrity, a billionaire who doesn’t need campaign contributions from anyone. But not everyone who follows will be able to stand up for the public interest in a system in which one interest, business, is muzzled while another, labor, is allowed to funnel tens of thousands of dollars in contributions designed to influence policy.