Every day, people beep their horns to support candidates or causes, greet friends or neighbors, summon children or co-workers, or celebrate weddings or victories. This expressive conduct is common, widespread, and protected by the First Amendment. It is an especially important medium of expression when public health restrictions curtail other forms of assembly and protest. Yet California Vehicle Code § 27001 bans all expressive horn use regardless of time, place or volume, except to convey messages of “audible warning.” At the same time, the statute allows horns to be used as theft alarms.

Beginning in July 2017, Susan Porter participated in weekly protests against Representative Darrell Issa at his then-district office in Vista, California. On October 17, 2017, after deputy sheriffs arrived and issued parking citations to protesters and counter-protesters, she moved her car away from a fire hydrant and beeped her horn to support the protest.

A deputy sheriff then stopped and cited her for violating § 27001. Although the citation was dismissed when the deputy failed to appear in court, she continues to censor herself from using her horn to support protests.

With co-counsel Foley & Lardner LLP, we filed suit in June 2018 to challenge the enforcement of § 27001 against protected expression. After the trial court ruled against us, we appealed to the Ninth Circuit, with support from an amicus brief authored by G.S. Hans, Director of the Stanton Foundation First Amendment Clinic at Vanderbilt Law School, with and on behalf of the First Amendment Coalition.

We argue § 27001 violates the First Amendment because it discriminates on the basis of content, allowing drivers to give warnings but not support protests. Even if the statute is content neutral, it is unjustified by any evidence that expressive horn use has ever caused a single accident or hazard or necessarily exceeds ambient noise levels regardless of time, place or volume.

Any interest in noise prevention is difficult to credit given that the statute allows horns to be used as theft alarms that can shatter a quiet night. But even if noise is sometimes a legitimate concern, enforcement of other laws can prevent genuinely excessive noise without stifling protected expression.

Free speech is the oxygen of civil society. Regardless of motivation, any official restriction on expression in the name of concerns such as safety or noise must be justified by robust evidence and narrowly tailored to address the precise problems at issue.

Otherwise, the risk is too great that government may abuse its power to silence protest and dissent. As the Supreme Court said over 70 years ago, “Annoyance at ideas can be cloaked in annoyance at sound.” The First Amendment does not permit government to retain such unchecked power.

Press release: https://www.aclusandiego.org/en/news/aclu-ca-law-used-cite-drivers-who-honk-their-horns-during-protests-unconstitutional

Complaint: https://www.aclusandiego.org/sites/default/files/wp-content/uploads/2018/06/2018-06-11-D1-Porter-Complaint.pdf


David Loy, Legal Director Foley & Lardner LLP: J. Mark Waxman, retired partner; Mikle S. Jew, associate; Kadmiel E. Perez, associate; Lindsey L. Pierce, associate

Date filed

June 11, 2018


Southern District of California, Ninth Circuit


Gonzalo P. Curiel



Case number

18-cv-1221 (district court), 21-55149 (Ninth Circuit)