By Jeremy W. Peters

ALBANY — As political rituals go, it was one of Albany’s most predictable.

Every two years, a state law that required public employees to pay their unions’ dues regardless of whether they joined would near expiration. And every two years, the Legislature would renew the law. For more than three decades, unions pushed to make it permanent. But lawmakers, mainly Republicans in the State Senate who wanted the Legislature to have some degree of leverage over the state’s powerful public sector unions, blocked those attempts, arguing that a permanent extension of the law would amount to a big giveaway to organized labor.

Now, Gov. David A. Paterson has given the state’s public-employee unions their long-desired victory. On Wednesday, his office announced that he had signed a law making union dues mandatory in perpetuity for all public employees who are covered by unions even if they opt not to join.

The law affects mostly state workers, as well as county employees, public school teachers and other civil servants.

The Legislature overwhelmingly approved the bill last month. Similar bills had passed the Democrat-controlled Assembly before, only to fail in the Senate. But with Republicans in a pitched battle to preserve their thin majority in the Senate, the party seemed unwilling to block a priority of organized labor.

It passed the Senate last month by a 62-to-0 vote. The Assembly approved it 140 to 5.

Labor leaders said on Wednesday that making the law permanent guaranteed that unions would have the money to adequately represent members and nonmembers alike, which they were required to do under a state law known as the Taylor Law.

“In public employment, they have the right not to belong, but I still must represent them,” said Richard C. Iannuzzi, president of New York State United Teachers. “If under the law we’re obligated to represent every employee, then it’s only fair that every employee pays something toward the cost of being represented.”

But critics of a permanent policy said that the new law was far too generous.

“It’s a very, very significant present to the labor unions,” said Edmund J. McMahon, director of the Empire Center for New York State Policy at the Manhattan Institute, a conservative-leaning research group.

“What it does is it removes one of the few remaining leverage points people still have over unions. And management, which is the taxpayer, has very, very little remaining leverage.”

A spokesman for the governor, Errol Cockfield, pointed out that because the law had been renewed every two years since 1977, the first year it was enacted, it has long been de facto state policy.

He added that in the governor’s estimation, it was a fair practice to make employees who declined union membership but were nonetheless represented pay dues.

Others said the law was a major concession to organized labor, which has been criticized as getting its way far too often in Albany. Earlier this year, the Legislature approved — over the objection of New York’s mayor, Michael R. Bloomberg — a bill that banned student test scores from being factored in when tenure was being considered for teachers.

The New York State School Boards Association, which urged Mr. Paterson to veto the union dues legislation, said in a letter to the governor that the bill amounted to “denying school districts an important bargaining tool.”

The association added, “This legislation grants employee unions one of their primary bargaining goals without requiring that they negotiate for it.”

Darcy Wells, a spokeswoman for the New York State Public Employees Federation, rejected that.

“Finally, the governor has stepped up and made it permanent,” Ms. Wells said.

“This has been a long time coming, and we think it’s the right thing to do.”