It may not get the attention of the impending Obamacare decision, but today’s Court’s decision in Knox v. SEIU is an important and somewhat unexpected victory for the First Amendment.

In 2005, the SEIU initiated a mid-year campaign against two California ballot measures, one that would cap state spending and another that would restrict the use of union dues for political purposes. In states such as California that do not have “right to work” laws, unions are allowed to take dues from non-union workers to finance collective-bargaining activities that, arguably, benefit all employees. Since 1977, however, unions have not been allowed to take dues from non-union members to pay for pure political advocacy without adequate protections for possible dissenters. In order to distinguish political money from collective-bargaining money, the Supreme Court requires that a “Hudson notice” be given to all non-union workers. This notice gives non-members the opportunity to challenge political expenditures.

The narrowest question in Knox was whether the notice given by the SEIU Local 100 complied with the Supreme Court’s requirements. There was a broader question, however, pushed by Cato in our brief (joining the Pacific Legal Foundation, the Center for Constitutional Jurisprudence, and the Mountain States Legal Foundation), on whether only having the ability to “opt-out” of political spending (rather than to “opt-in”) violates the First Amendment (Tim Sandefur of PLF offers his thoughts here). Opting-out presumes that the non-members want to engage in the union’s political advocacy, and this seems to place the burden on free speech on the wrong party.

In a decision that rings with a chastising tone directed at the union, Justice Samuel Alito affirmed that opting-out can be a First Amendment violation. In his words: “Our cases have tolerated a substantial impingement on First Amendment rights by allowing unions to impose an opt-out requirement at all.” Justice Alito also adopts our argument that balancing the rights of individuals with the “rights” of unions is the wrong way to look at the issue. Unions have long argued that complying with administrative requirements to give notice to non-union members impinges on their ability to be effective political advocates. Moreover, the unions argue, sometimes it is not possible to accurately determine what percentage of their funds will be used for political advocacy and “there is at least a risk that, at the end of the year, unconsenting nonmembers will have paid either too much or too little.” “Which side should bear the risk?” asks Justice Alito. “The answer is obvious: the side whose constitutional rights are not at stake.”

In this case, the First Amendment violation was particularly troubling because the union exacted money from nonmembers in order to defeat a California proposition that would have bolstered nonmembers rights. “If Proposition 75 had passed,” writes Alito, “nonmembers would have been exempt from paying for SEIU’s extensive political projects unless they affirmatively consented. Thus the effect of the SEIU’s procedure was to force many nonmembers to subsidize a political effort designed to restrict their own rights.”

Although the decision does not go so far as to require that unions must always use an opt-in procedure when extracting political war-chest money from nonmembers, it takes a very strong step in that direction, as Justice Stephen Breyer argues in dissent. Opting-in will only be required for such “special assessments” as in this case or for a general “dues increase.”

But Justice Breyer is correct that the majority opinion offers few reasons why opting-in should not be required for all union political dues taken from nonmembers, not just special assessments. In making the strong argument that forced speech without affirmative consent is a First Amendment evil, Justice Alito leaves little room for even the existing opt-out system. Alito and the justices who joined his opinion seem very friendly to the idea that all union political dues for nonmembers require opt-in procedures. Hopefully that case will hit the Court soon. For now, congratulations to Jim Young and National Right to Work Legal Foundation on an important victory.