Is it illegal to flash headlights to warn of police in Australia?

“When there is a danger present that oncoming drivers cannot be warned about via any other practical method (for example, a major collision where the road is closed, or a large number of livestock obstructing the road ahead), it may be permissible to warn oncoming traffic by flashing your headlights,” said the spokesperson.

When overtaking, you’re encouraged to briefly flash your headlights to warn the driver ahead of your intentions. In very Top End-specific advice, if you get overtaken by a road train, you’re also encouraged to flash your lights once the last trailer has passed, to let the driver know it’s safe to re-enter the left-hand lane.