As the nation debates the implications of the latest round of Supreme Court decisions, the court is already preparing a new slate for next term. Among the many cases on the docket, one stands out for its potential to eliminate a longstanding violation of citizens' First Amendment rights and pave the way for education reform.

In Friedrichs v. California Teachers Association, the Supreme Court will consider the constitutionality of state laws that compel public-sector workers to financially support unions. Ten California teachers argue that the state's "agency shop" law — which forces them to pay either union dues of about $1,000 per year or "agency fees" of about two-thirds that amount — violates their First Amendment rights.

Unions have long argued that the government must compel workers to join unions to prevent nonmembers from freeriding on the supposed benefits from their collective bargaining. In the 1977 case of Abood v. Detroit Board of Education, the Supreme Court ruled that states could only force nonunion members to cover the costs of collective bargaining, but not "to contribute to the support of an ideological cause [they] may oppose as a condition of holding a job."

In the spirit of Abood, California and 25 other states compel nonmembers to pay fees to cover the costs of public-sector unions' collective-bargaining activities, but not the costs of their explicitly political spending. But as the Friedrichs plaintiffs point out, public-sector collective bargaining is inherently political because it aims to influence government policies.

The Supreme Court appears inclined to agree. Last year, the court ruled in Harris v. Quinn that publicly subsidized home healthcare workers — which often include relatives of the elderly or infirm — couldn't be compelled to join a union. In the process, the court's majority questioned the logic of Abood, noting that in the public sector, "core issues such as wages, pensions, and benefits are important political issues." Every dollar a city spends on teacher pensions is a dollar it doesn't spend on parks or police. Whether through TV ads or across the negotiating table, efforts to influence government policies on such issues constitute political speech.

Agency-shop laws force people to financially support political views with which they disagree or lose their jobs, an obvious First Amendment problem. As the Supreme Court has held countless times, the freedom of speech includes the right not to support someone else's speech. Unions shouldn't be able to force nonmembers to finance their activities just because the union thinks they'll benefit. As the court noted in Harris, "preventing nonmembers from freeriding on the union's efforts" is a rationale "generally insufficient to overcome First Amendment objections."

The end of compulsory agency fees in the public sector could have a tremendous impact on public policy, particularly in the realm of education. Deep-pocketed teachers unions are among the most formidable obstacles to education reform. In the 2014 election cycle alone, the National Education Association and American Federation of Teachers spent a combined $60 million on contributions to politicians and outside advocacy groups in addition to the undisclosed amount they spent on lobbying.

Although more than a dozen states adopted new or expanded school-choice programs so far this year, teachers unions have played a key role in blocking several promising initiatives. In New York, the largest teachers union took credit for defeating Governor Cuomo's proposed Parental Choice in Education Act, which passed the state senate and had the declared support of a majority of state assemblymen. Nevertheless, the union's allies in the assembly speaker's office made sure the bill never received an up-or-down vote. The unions also successfully blocked similar legislation in Texas despite the support of the governor and state senate, as well as programs in Colorado, Oklahoma, Montana, Virginia and elsewhere.

Moreover, a recent survey by Harvard University's Program on Education Policy and Governance found that six in ten Americans support tax-credit scholarship laws like those proposed in New York and Texas, including nearly four in ten teachers. Sadly, those teachers are forced to pay the unions to work against their preferred policies — that is, until the Supreme Court rules otherwise.

Mr. Bedrick is an education policy analyst and Mr. Shapiro a senior fellow in constitutional studies at the Cato Institute, which filed a brief supporting the petition for Supreme Court review in the Friedrichs case.Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.