Americans for Prosperity Foundation and the Thomas More Law Center are charitable organizations who advocate for a variety of free-market and socially conservative viewpoints that are controversial in the current political climate. As nonprofits, they fund their activities through private donations from like‐​minded individuals across the country, many of whom prefer to remain anonymous for fear of public reprisal. These fears are well-founded: people associated with AFP and Thomas More have experienced threats, harassment, boycotts, and even violence because of their views and affiliations.

In 2010, the California attorney general’s office began demanding that all charities that fundraise in the state turn over their IRS Form 990 Schedule B. A Schedule B is a highly confidential form that lists the names and addresses of a charity’s major donors—including those who live outside of California. Although the attorney general’s office claimed that it would keep Schedule Bs private, systematic incompetence and a lack of safeguards have led to repeated and widespread leaks of the documents to the public.

AFP and Thomas More each refused to give California their Schedule Bs and filed lawsuits to protect their donors’ anonymity. Both charities won at the trial-court level, where a federal judge found that the disclosure requirement violated the donors’ First Amendment rights. The U.S. Court of Appeals for the Ninth Circuit reversed those judgments in both cases, however, prompting a sharp dissent from several judges.

The dissenters argued that the court had made “crucial legal errors” by going against decades of Supreme Court precedent and refusing to apply what is known as “narrow tailoring.” Narrow tailoring is a common‐​sense requirement that the government carefully craft laws so that they infringe as little as possible on fundamental rights. AFP and Thomas More each petitioned the Supreme Court to hear their cases, with Cato filing a supporting brief.

The Court agreed to hear the cases together. Joined by eight other organizations, Cato has again filed an amicus brief in support of these petitioners. We argue that the Court should reverse the Ninth Circuit because the Constitution protects the right to private, anonymous association and the burden is on the government to overcome that protection with a compelling interest that’s advanced through narrowly tailored means. Indeed, the Court set that standard in the seminal 1958 case NAACP v. Alabama, rebuffing the state’s attempt to get the civil rights organization’s membership list.

Defending private association is not about protecting the powerful, who have more often used government to go after those who challenge prevailing orthodoxy. The risks to donors can be real, which is why forced disclosure regimes are often driven by an inappropriate goal: the silencing of political speech. We urge the Court to reaffirm its long-standing protections for First Amendment rights.

The Supreme Court will likely hear argument in Americans for Prosperity v. Becerra and Thomas More Law Center v. Becerra next month.