Suppose a police car is stopped at a green light and not moving. Is it illegal for me to honk at him? What if I can't drive around him?

What if it happens to be a civilian vehicle and a plainclothes officer? Is it illegal in this case?

I see several videos of uniformed and plainclothes officers stopping cars for honking at them.

As a context I'm giving a link to this video:


I find this video shocking behavior behavior from the police. But I want to know legally what's allowed and not allowed. Is the police legally allowed to stop at a yield sign for police related business which is a phone call?

  • 1
    This is probably going to depend on a myriad local laws...
    – Nemo
    Jul 9, 2023 at 7:04
  • @Nemo I'd say it's going to depend in the cop's ego. There are many video's online about cops reacting to things that are legally protected free speech, with the sole issue being it hurt someones feelings. (not saying that all cops are like this, but selection bias of youtube videos shows that it does exist)
    – Peter M
    Jul 10, 2023 at 19:18
  • He honked while the cop was still blocked from entering the roundabout by a truck in the intersection. Jul 10, 2023 at 19:38
  • @MichaelHall, yes you're right. Motorcycle rider had no patience. Probably not the best video to use as an example. Jul 10, 2023 at 20:05

3 Answers 3


In England, the use of a horn when stationary is restricted solely to advise other road users of your presence "at times of danger". Not spotting that the light has gone green would certainly not fit that description.

Use of audible warning instruments

99.—(1) Subject to the following paragraphs, no person shall sound, or cause or permit to be sounded, any horn, gong, bell or siren fitted to or carried on a vehicle which is—

(a) stationary on a road, at any time, other than at times of danger due to another moving vehicle on or near the road...

The Road Vehicles (Construction and Use) Regulations 1986

The policeman would be well within his rights and duties to provide you with a fixed penalty notice of £30.

  • Thanks. So in practice... suppose a driver hasn't seen the green light and isn't moving. Do people generally honk the horn anyway even though it's illegal? Or do people just wait? Jul 9, 2023 at 10:00
  • 3
    @AmeetSharma - Oh, sure. People honk for all sorts of reasons that are specifically excluded by the Highway Code, including prompting other drivers. They just shouldn't complain about it when they do it to a copper and get fined since that falls under the heading of 'self-inflicted stupidity'.
    – Richard
    Jul 9, 2023 at 10:00
  • 4
    Would a police officer behind you, honk at you if you're not moving at a green light? Jul 9, 2023 at 10:08
  • 1
    @AmeetSharma - I'd encourage you to not accept my answer. Your question is about the US, and while answers from other jurisdictions are welcome, the core question is still yet to be answered
    – Richard
    Jul 10, 2023 at 10:53
  • 2
    @AmeetSharma Many common things are illegal. Many people, including cops, do those things. Many of those people are never caught, and if there are caught, the harshness of the punishment depends more on the cop’s feelings than the objective factual circumstances. Just because "everyone does X" does not mean X is legal (at best it means than X is considered morally acceptable in society, and maybe it should be made legal, but that’s a question for another stackexchange).
    – KFK
    Jul 10, 2023 at 16:23

In Germany, the horn can only be used for two reasons:

  • As a signal for overtaking outside of city limits only.
  • As a warning signal for imminent danger.

So, in the situation described in the question, it would be illegal to honk at the police officer, but the fact that they are a police officer is actually irrelevant – it would be illegal to honk in that situation, period.

  • Thanks. So at a green signal, if a car in front of you isn't moving... do people traditionally just wait without honking? Jul 9, 2023 at 10:00
  • 2
    At a green signal, if you haven't started to move within milliseconds, everybody will honk and flash their high-beams at you, accompanied by some choice words and gestures not suitable for children. Jul 9, 2023 at 10:04

: Yes, unless

  • you are outside a city
  • it is daytime
  • you can convince the cop or the judge that doing so is a "necessary warning for other road users". Not my specialty, but barring extraordinary circumstances, I expect that defense to fail.

Code de la Route, articles R416-1 and R416-2:

Hors agglomération, l'usage des avertisseurs sonores n'est autorisé que pour donner les avertissements nécessaires aux autres usagers de la route.

En agglomération, l'usage de l'avertisseur sonore n'est autorisé qu'en cas de danger immédiat.


De nuit, les avertissements doivent être donnés par l'allumage intermittent soit des feux de croisement, soit des feux de route, les signaux sonores ne devant être utilisés qu'en cas d'absolue nécessité.

Outside city limits, klaxon may be used solely to give necessary warning to other road users. [For instance, when driving around a mountainous road, you are supposed to honk when approaching a curve without visibility, so as to warn drivers coming ahead.]

Within city limits, klaxon may be used only in case of immediate danger.


At night, signals must be given by flashing headlights, klaxons must only be used in case of absolute necessity.

Failing to respect those rules is a second-class contravention (currently set at €35). Technically, those apply to any vehicle, including bikes (even if bike klaxons are much less noisy than car klaxons).

While in theory it is irrelevant whether there is a cop in the car in front, behind, or sideways of you... I imagine less than 0.1% of wrong klaxon uses are penalized, and all of those occur when a cop was on-site.

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