Ten teachers and the Christian Educators Association International are suing to block a California law requiring teachers to pay union dues even if they aren’t union members, a lawsuit that could potentially weaken some of the most powerful unions in the state.

The Center for Individual Rights filed the lawsuit. “Forcing educators to financially support causes that run contrary to their political and policy beliefs violates their First Amendment rights to free expression and association and cannot withstand First Amendment scrutiny,”  the nonunion teachers’ attorney, Michael A. Carvin, said in a statement.

Carville pointed to a 2012 Supreme Court ruling that the Service Employees International Union could not raise fees on nonunion members in order to finance opposition to local ballot initiatives.

“Because a public-sector union takes many positions during collective bargaining that have powerful political and civic consequences, the compulsory fees constitute a form of compelled speech and association that imposes a significant impingement on First Amendment rights,” Supreme Court Justice Alito wrote in the majority opinion.

The fight over nonunion dues is playing out in state legislatures, as well. Last week, “the Vermont House voted 78-51 on Thursday to impose union fees on about 2,600 non-union education, state and municipal employees,” per VTDigger.

In December, Michigan went the opposite direction when Gov. Rick Snyder, R-Mich., signed a right-to-work bill passed by the Republican-controlled House and Senate.