Rebecca Friedrichs is an Orange County, Calif., math teacher who pays about $700 to her union every year. She didn’t sign up for that expense, though. Under California law, she has no choice: Public school teachers either enroll or they don’t work.

If she gets her way in court, however, she won’t have to pay dues much longer. She is one of 10 educators suing the California Teachers Association to end the dues requirement.