Over the past 200-plus years, the U.S. Supreme Court has carefully guarded Americans against laws or government actions that intrude on free speech, including laws that force us to support speech with which we disagree. Overall, the court has done a good job of striking a balance between individual freedom and the need of government to keep the public peace. But the court does not always get it right.

One mistake concerns the speech rights of public employees in relation to public unions. While the court has recognized that public employees cannot be forced to join a union to keep their jobs (this violates their right of free association), the court ruled in Abood vs. Detroit Board of Education in 1977 that forcing public employees to pay an "agency fee" to cover the costs of representing them did not violate the First Amendment. As a result, unions, which set their own agency fees, have collected about 85 percent of dues to cover a "fair share" of collective bargaining costs in Minnesota.

Prior to the late 1950s, public unions were banned as a matter of good public policy. In 1977, when Abood was decided, public unions were just beginning their ascent among the most dominant players in national and state politics. So it is perhaps understandable that the court viewed an agency fee as fair, even benign. Today, public unions are involved in negotiating salaries and benefits, but also in lobbying over everything from education policy to pension policy to taxes and budgets.

Since the Abood decision, the court has fiddled with agency fees in an attempt to separate political spending from pure collective-bargaining costs, and found it a difficult if not impossible task.

In two very recent cases (Knox vs. SEIU, and Harris vs. Quinn), the court's growing discomfort with mandatory agency fees was so apparent that court watchers predicted a public employee would soon appear before the court to challenge those fees.

Enter teacher Rebecca Friedrichs from California. On Monday, Friedrichs will ask the court to end mandatory agency fees on the grounds that everything public-sector unions negotiate for is inherently political. And because the union's actions are inherently political, she should not be forced to fund the union in order to keep her job.

Friedrichs does not want a "free ride," as unions have argued. She simply wants the right to choose whether or not the California Teachers Association, a dominant political spender and shaker in her state, deserves a portion of her paycheck.

Many teachers and other public employees in Minnesota are faced with this same stark choice: Do I pay agency fees to a political organization that defeats me at the ballot box and the Legislature? Or do I leave my job? Half of the states in the U.S. are so-called "right-to-work" states, where employees are free to decide whether a union provides value to them. The other half of states, like Minnesota, still force employees to support unions.

The Friedrichs case is not an assault on public unions. But if Friedrichs wins, public unions like Education Minnesota will have to stop taking their members for granted if they want to keep collecting fees and dues. An organization that can compel its members to fund its mission is bound to grow arrogant.

The Friedrichs case is a heartfelt objection to the prejudicial idea that giving up one's First Amendment rights in exchange for a job is fair. It is an opportunity for the court to get this one right.

Kim Crockett is executive vice president and general counsel of the Center of the American Experiment.