Conservative U.S. Supreme Court justices on Monday voiced support for a legal challenge that could erode organized labor's clout by depriving public-employee unions of millions of dollars in fees that many state laws force non-union members to pay.

Justices John Roberts, Anthony Kennedy and Antonin Scalia indicated during an 80-minute oral argument that they could join the nine-member court's two other conservatives to overturn a 1977 high court precedent allowing the fees, a vital source of funds for the unions.

Legal experts had thought Scalia might be sympathetic to the union position due to prior votes and statements on the subject, but his questions signaled support for the 10 non-union California public school teachers who challenged the fees.


U.S. conservatives have long sought to curb the influence of unions representing public employees like police, firefighters and teachers that often support the Democratic Party and liberal causes.

A ruling allowing non-union workers to stop paying "agency fees" equivalent to union dues, currently mandatory under laws in about half the 50 states including California, could strip public sector unions of millions of dollars, reducing their income and political power.