Dan Janison Melville. N.Y. Tuesday January 26, 2010. Daniel Janison,

Dan Janison has been a reporter at Newsday since 1997.

Four years ago Wisconsin Gov. Scott Walker drew cheers from fellow Republicans -- and denunciations from Democrats -- for sharply paring the bargaining power of his state's public-sector unions through legislation.

Last March, as Walker geared up to run for the GOP presidential nomination, he signed a law barring employees from being required to pay union dues.

Walker quit the national race last month, but the political winds on which he has sailed still blow.

The U.S. Supreme Court, in the fall term that opened this week, is due to decide a case that could sharply disempower municipal labor organizations in a way that Walker or any other state official never could.

Oral arguments are scheduled for the next few weeks in Friedrichs v. California Teachers Association. Depending how it breaks, the decision, due by June, could prove almost as resonant as the Obamacare and same-sex marriage rulings.

All around New York, Friedrichs is the talk of anxious civil-service union leaders.

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Some basics:

Ten California teachers filed suit claiming that "agency shop" laws, requiring public employees to pay union dues as a condition of employment, violate free speech and association.

A right-leaning libertarian group called the Center for Individual Rights is in their corner.

"While many teachers support the union," CIR states on its website, "others do not and the state cannot constitutionally compel an individual to join and financially support an organization with which he or she disagrees."

If that claim prevails, unions could see their revenue severely sliced. A New York labor consultant who declined to be identified said: "It could even force one of the smaller organizations to go under -- like if a third of its 3,000 members refuse to join or pay dues.

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"They don't like losing those dues -- it's what they live off of."

Union activists see the worst-case scenario coming out of Freidrichs as a national "right-to-work" law for public employees.

E.J. McMahon of the conservative Empire State Center for Public Policy predicts that if the high court sides with the dissident teachers, there may be no fiscal impact in the short term.

"But in the long run, it would significantly alter the balance of power" against unions and toward taxpayers, he said.

In 1977, the Supreme Court ruled in the case of Abood v. Detroit Board of Education that unionized public employees may be excused from paying the portion of their dues that go to political activities such as backing chosen candidates. "But crucially," the court "also held that represented workers may be required to pay for their share of union bargaining and contract enforcement," wrote Charlotte Garden, an associate professor at Seattle University School of Law and Litigation.

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Employees who work under a union contract but don't pay dues are known in labor lexicon as "free riders."

Garden said in an article published in August: "It is an exaggeration to say that public-sector unions will cease to exist if the Court holds that [agency shops] are unconstitutional.

"At the same time, it is certain that disruption and discord will result within otherwise stable bargaining relationships as unions attempt to compensate for inevitable free riding."