I don’t know who it was that told me about the unwritten and unspoken rule of the road — if you saw a police officer sitting and waiting to catch people going quickly in the opposite direction, and you saw people coming in that direction that you were encouraged, if not obligated, to warn the drivers headed toward the speed trap by flashing your headlights a couple of times.

Under ordinary circumstances, the person receiving the warning can only respond in one of two ways. Either they are aware of what the warning means and slow down, or they are not aware of what it means and continue driving as they were and possibly get pulled over for speeding. If they are wise enough, at that point they figure out why someone flashed their lights at them. I would imagine if they do not quite get it at that point, they never will.

It has never been on the books as a legal thing to do, however — not that it was on the books as an illegal thing, either. One driver got pulled over for unlawful use of his high beams and when he filed a lawsuit after getting ticketed for this reason, it was considered to be quite a big victory for civil rights.

If you were walking down the street and saw a police officer crouching behind some bushes, waiting to jump out and arrest passersby, would it be considered illegal to write “POLICE OFFICER IN BUSHES” on a large sign and to walk in the area with it? It absolutely would not be — it most certainly would fall under the banner of free speech, just as flashing high beams can be considered a form of expression regardless of what is being expressed.

Hopefully the victory in this lawsuit means that it will be recognized in other states — if you see a police officer, you can flash your high beams to warn other motorists. After all, we have been told for well over ten years that if we saw something to say something — and why would they want us to stop at just the things that they deem relevant?


  1. I’m not sure what the point of this sort of control is supposed to be in the end. For decades, truckers have been warning each other, and other interested motorists, via CB radio when police are in and around the area.

      1. Control:

        One driver got pulled over for unlawful use of his high beams and when he filed a lawsuit after getting ticketed for this reason, it was considered to be quite a big victory for civil rights.

        1. I suppose you could say the police hope to discourage people from warning each other about the police presence — not that such discouragement works!

          Incidentally, how does block quoting look on your end? Over here it looks like plain, ordinary text. I only know the text is block quoted because the notification e-mail shows HTML.

  2. This has always been a way of life and unwritten rule of the road in the UK and one that is common in Portugal. It has always been considered common courtesy to warn other drivers of any potential hazzards which may require them to pay extra care – such as wide loads, livestock in the road or crossing the road, a group of cycle riders, pony and carts, slow moving vehicles , accidents and of course speed traps. The point being it is ANY and ALL hazzards, anything that causes cars to tail back and could make the oncoming driver brake suddenly and possibly cause a tail to tail knock on accident .

    In Portugal especially flashing lights is also a common form of Hello ……………

    Do you have a national driving code like the UK does – or does it differ state to state ?

    1. Good to know that people are so good about warning others!

      There are laws that are binding for everyone in the country, and in addition there are state laws — and, if I am not mistaken, there are even laws that pertain only to certain cities and counties!

  3. Just stopping in to say I’m using Firefox and I don’t see any blockquote format in the comments either.

  4. I’ve heard flashing warning brights called “The Paul Revere Syndrome” in law enforcement circles. 🙂

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