Drivers could be fined up to £1,000 if they try to send a warning to other motorists about police speed traps.
Road users who try to help out their fellow drivers by flashing their lights as a speed camera warning could be fined a four figure sum, according to a new study.
As part of the Highway Code, drivers are instructed to use their headlights "only to let other road users know that you are there" and not to attempt "to convey any other message".
If drivers are warning others about a police speed trap, they could be in breach of section 89 of the Police Act 1997 - reports Birmingham Live.
This law states that it's an offence to "wilfully obstruct a constable in the execution of his/her duty".
And the warning does not just relate to the road itself, but social media too.
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As well as flashing your lights to warn other drivers, this could also apply if you post the location of a police speed trap on social media channels, like Facebook, Twitter and Instagram.
In recent months, traffic and travel groups on Facebook have gone from strength to strength, with some boasting thousands and thousands of members.
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The groups share traffic details, like road accidents, delays and queues, as well as tell each other parking tips and more.
But if you share the information of where you have seen police speed traps you could be left out of pocket, if police decide to fine you.