Is it Legal To Flash Your Headlights To Warn About Speed Checks?

Is it Legal To Flash Your Headlights To Warn About Speed Checks?

You’re driving home in the afternoon and on the way back you spot an unmarked cop car parked by the side of the road doing speed checks. Instinctively, you flash your headlights to warn oncoming drivers about the speed trap ahead. Seems normal enough, but is this act of goodwill legal?

Headlights image from Shutterstock

Flashing your high beams to warn others of hazards and police on the road ahead is an unspoken road etiquette that most Australian drivers know about. While there aren’t any specific laws nationally that deal with flashing headlines to alert others, there are strict rules in place when it comes to the use of high beams.

As stipulated in the Australian Road Rules (2006) Section 218 for the use of high beams:

(1) The driver of a vehicle must not use the vehicle’s headlights on high-beam, or allow the vehicle’s headlights to be used on high-beam, if the driver is driving:
(a) less than 200 metres behind a vehicle travelling in the same direction as the driver, or
(b) less than 200 metres from an oncoming vehicle.

When you flash your headlights as a warning, it usually occurs within the distance limits stipulated in the legislation so, technically, it is illegal. In fact, the Queensland police has used this rule to issue fines and incur demerit points to drivers who flash their high beams to warn others of speed camera and law enforcement vehicles ahead.

Meanwhile, in Victoria, police are fine with drivers flashing their headlights to warn others of speed cameras. So the law on high beam use is adapted by law enforcement agencies in different states accordingly but police are technically allowed to penalise you if you do flash your headlights as a warning to other drivers.

Did you just catch yourself wondering if something was legal or not? Let us know and we may be able to answer it in our next Is It Legal? feature.


  • Flash them just as you are passing them. Enough to notice, doesn’t shine in their eyes.

    In my younger days I was a bit enthusiastic and flashed someone about 5 times. When they got closer it was a cop car. They just kept going. Tasmania.

  • I do it all the time if I see a car speeding or hooning , it slows them down for a bit thinking there is a copper ahead. Dont need idiots on the road.

  • but police are technically allowed to penalise you if you do flash your headlights as a warning to other drivers.

    See, this is where it gets dodgy for me. I don’t normally believe in the term ‘revenue raising’, but if something is ‘technically’ allowed, then it should be clarified. It either is or it is not. Because that means the decision can be abused. If I turn my low beams on, off, on, off etc, then I am not breaking the law. But, high beam, sure I am breaking the law. But if I do low beam, why should I be penalised, for not breaking the law?

    • Enh. I figure it’s probably like jaywalking. You very rarely see enforcement teams out and about, outside of a few hotspots known for causing problems with traffic.

    • Having spent some time there, they sure do. Usually it’s because you’re only doing 20 over the speed limit in front of them and they’re doing 40 or more over.

      • Agreed.

        I’m from SA, and QLD drivers crawl around the roads like old grannies.

        It seems QLD drivers can’t be bothered paying attention to the speed limit signs, and just drive at 50 km/h or less… everywhere, even when the speed limit is 60, 70 or 80. Do this in the USA and you will be fined for obstructing the traffic.

  • So what if I flash my lights to warn another driver of a hazard (ie not a speed trap) in the road ahead?
    If this rule still applies, then I should just let them plow into that herd of cattle around the next bend?

  • That’s what technically means here. You are not legally allowed to flash your headlights. The law is in place to stop you blinding other motorists. Like most laws or can be applied to unindented things like completely safe flashing discussed here. Also turning your lights on and off I.e. not high beam is completely legal

  • I never flash my headlights to warn motorists about speed cameras. My reasons are that if a speeding motorist avoids a speeding fine due to my actions they would likely speed up again. After doing so, they are at more of a risk of hitting a pedestrian, another car or a tree. I’d rather the get the fine and learn a lesson than potentially kill someone due to my intervention.

    • I am the opposite to you then.
      I tend to speed after passing a speed trap because they really piss me off. Could be out stopping crimes instead of taking $190 of my hard earned.
      And yes you can always reply with “do the crime, do the time”, but is it really a crime? I drive to conditions. If I come off the highway and haven’t reached 60 yet its not really a crime against humanity is it? I still go less than 40 near some schools.

  • There’s a temporary highway sign near my house at the moment which alternates saying: “police enforcing speed”, and “high risk area”.
    My question is: high risk of what?
    The only 2 bad accidents in the immediate area within the last 2 years were elderly drivers screwing up.

    • I love the Police Enforcing Speed signs, always make me laugh driving to Melbourne. “I’m sorry officer, the sign said you were enforcing speed so I sped up when I saw your lights”.

  • Light sensitivity is relative. Hi-beams are only blinding at night because your eyes (irises) are open wider and are pulling in more light. So this law should really only apply to night driving.

    On top of that, in most halogen headlights, the bulbs come up their full brightness over about half a second or so. A flash is usually only a quarter of a second, so they are not at full brightness. They will only dazzle you if they are held on.

    In short, any officer booking you for use of your high beams in this manner is probably having a bad day.

  • I remember Carl O’Callaghan (WA Police chief) saying that WA police don’t care if people flashing their lights, and actually encourage it, if it means people stop speeding.

  • I don’t flash anyone. If you are stupid enough to speed, you are stupid enough to deserve the fine. The roads are already full of incompetent people who cannot obey the road rules (but claim they are driving to the conditions). Let the stupids get fined, give their money to the state (when they don’t have to), and eventually they gain 12 demerit points so they are off the roads for awhile. 1 less stupid person on the road.

  • Sweet, so long as I use my low beams in QLD, there’s nothing to worry about. I hate the Police and their sneaky revenue raising tactics, they always put cameras on long flat straights, bottom of hills etc. There is a thing called safe speeding, I do it everyday and have never been involved in an accident . Slow incompetent drivers cause accidents, sitting in the outside lane blocking people from overtaking!. Now they’re the ones who should lose their license!

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