There is no reason to discuss, in the context of an applied challenge, whether the regulation is subject to a construction of constriction. If the regulation is invalid in the form applied, we should simply overturn the convictions of the accused, since the regulation is not invalid in toto.  Florida Statutes 316.271 – Horns and Warning Devices – No horn or other warning device may emit an inappropriate and loud sound or whistle. No vehicle may be equipped with a siren, whistle or bell, and no person may use it in a vehicle, unless otherwise authorized in this section. 2012 South Carolina Code of Laws Section 56-5-4960 – Use of the horn – The driver of a motor vehicle shall, if reasonably necessary to ensure safe driving, give an audible warning with his horn, but may not use it elsewhere on a highway. Indiana Code 9-19-5-2 Use of the horn during vehicle operation – Section 2. The driver of a motor vehicle shall, where reasonably necessary to ensure safe use, give an acoustic warning with the horn on the motor vehicle, but shall not use the horn elsewhere on a motorway. § 3. (a) Except in the cases referred to in subparagraph (b): a vehicle may not be used and a person may not use it on a vehicle; a siren, pipe or bell. An authorized emergency vehicle may be equipped with a siren, whistle or bell capable of hearing under normal conditions at a distance of at least five hundred (500) feet and of a type approved by the Ministry. A siren authorized under this section may only be used if the vehicle is used unless the vehicle is used in response to an emergency call or to immediately pursue an actual or suspected violation of the law. A person who drives a vehicle equipped with a siren in accordance with this Section shall sound the siren when reasonably necessary to warn pedestrians and other persons driving vehicles of the approach to the registered vehicle.
The City of Eugene (city) replies that the order does not violate Section 8, either with respect to the face or in the form applied, “because it does not target speech. On the contrary, it is directed against the physical act of honking * [and] is constitutional because it is a regulation of time, place and path neutral on content that focuses on the effect of language. City proposes that the regulation protect the use of the car horn as a warning device. 2. Except as provided in this division, a vehicle shall not be equipped with a siren, hose or bell and a person shall not use it in a vehicle. A vehicle may be equipped with a flight warning device if it is arranged in such a way that it cannot be used by the operator as an ordinary warning signal. An anti-theft alarm signalling device may: use a pipe, bell, horn or other acoustic signal; and do not use a siren. An approved emergency vehicle shall be equipped with a siren, whistle or bell that can be audible at a distance of at least 500 feet under normal conditions.
The nature of the noise must be approved by the Ministry on the basis of the standards adopted by regulation under section 41-6a-1601. The siren of an approved emergency vehicle shall not be used except: when the vehicle is used in response to an emergency call; or in direct prosecution for actual or suspected violations of the law. The driver of an approved emergency vehicle shall sound the siren in accordance with this Section when reasonably necessary to warn pedestrians and other drivers of vehicles of the approach to the approved emergency vehicle. A violation of this article is a violation. Texas Transportation Code § 547.501. Audible warning devices – (a) A motor vehicle shall be equipped with a horn in good working order that emits noise under normal conditions at a distance of at least 200 feet. (b) A vehicle shall not be equipped with a siren, whistle or bell and a person shall not use a siren, whistle or bell in a vehicle unless the vehicle is: (1) a commercial vehicle equipped with a flight warning device so that the device cannot be used as an ordinary warning signal; or (2) an authorized emergency vehicle equipped with a siren, whistle or bell that complies with section 547.702. (c) A driver of a motor vehicle may use a horn for audible warning only when necessary to ensure safe use; (d) An alarm, including a horn, shall not emit an inappropriate and loud sound or whistle. South Dakota State Act 32-15-11. Sirens, whistles and loud noises unnecessary as offenses.
Except as otherwise provided in § 32-15-12, it is a Class 2 offence if a vehicle is equipped with a siren or compression whistle or spark plug or an exhaust horn or whistle that does not produce harmonic sound, or at any time a person uses a horn other than an adequate warning or sound unnecessarily or unduly loud or rough by means of a horn or other warning device. Triggering a mechanical device to produce a sound does not always represent a language. See, for example, State of Hibbard, 110 Or.App. 335, 339, 823 p.2d 989 (1991), rev. 313 Or. 211, 830 p.2d 596 (1992). However, the accused honked their horns to show their support or disapproval of a political issue or a matter of public interest. If they had shouted their consent or refusal of their car, that expression would be protected by Article I, Section 8.
Nevertheless, their expression is protected because it manifests itself in a mechanical sound, unless a significant safety or public health interest is at stake. See City of Portland v. Ayers, 93 Or.App. 731, 735, 764 p.2d 556 (1988), rev. 308 Or. 79, 775 p.2d 322 (1989). The regulation restricts any horn to any purpose at all times, except as a warning. For example, it is wide enough to make horns illegal if a motorist honks as a friendly greeting to a passerby in front of a residence, or in other circumstances where horns are used as a form of communication. The regulation is not limited to circumstances in which the public interest may be affected by noise or abuse. Because the ordinance regulates much more than the consequences of the behavior the city claims to want to prevent, it is unconstitutionally too broad. In January 1991, protesters staged protests outside the Federal Court building in Eugene in response to the Gulf War.