Cops, firetrucks, and ambulances - ALL GOVT entities, use horns. A LOT. Legally, and always have.
The President of the United States has REQUESTED people honk their horns at covid related drive-in rally in Philadelphia in which he encouraged people to "honk if you want to be united again" https://www.c-span.org/video/?477670-1/joe-biden-holds-drive-rally-philadelphia
The previous President heard horns honking from truckers in protest, and said it was a "sign of love"
so obviously the presidents have been in favor when it helps them in self promotion
The Supreme Court has repeatedly ruled that speech protected by the First Amendment encompasses more than the spoken word. In 1969 the justices ruled that students wearing black arm bands to protest the Vietnam War were taking part in protected speech. Seven years later, the court said that campaign contributions are a form of political speech. Burning the flag was found to be free speech. So, there is a lot of rulings and decades of traditional American culture of non-verbal "free speech" rulings by the court.
The state of California has stated in court: "Horn honking is very loud and distracting by design, and the restriction ... has been 'nearly universally accepted as a means to reduce the incidence of vehicular accidents' for more than 100 years," the state told an appeals court in 2021, partly quoting from a lower court's earlier decision in the case
The ACLU, probably the best known organization that once was the citizens best proponent of free speech fighting against the government, has written an article that brings up several good points, motivating me to make this article.
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. (Clearly, a double standard that necessitates a court ruling to hammer it out one way or another)
§ 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.
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.