TORONTO - It's a universal, unspoken code of the road: a quick flash of the high beams to warn oncoming motorists about a looming police speed trap. But is it illegal?

That act of common courtesy got a Toronto man a $110 ticket and has spurred debate about whether drivers are legally allowed to communicate via their headlights, and whether the police officer in question overstepped his bounds in interpreting the law.

Similar tickets have been fought all the way to the Supreme Court in Alberta and Pennsylvania. A quick web search turns up countless discussions of whether or not flashing the high beams is a crime.

Brad Diamond didn't think he'd done anything wrong when he was pulled over on a Saturday morning last year after flashing his headlights to warn motorists they were heading towards a police radar outpost.

The Toronto police officer told Diamond he'd violated a section of Ontario's Highway Traffic Act, which states "no person shall use high-beam headlamps that produce alternating flashes of white light on any vehicle" other than an emergency vehicle.

A few weeks ago he got his day in court and before watching two other drivers fight a similar ticket, his charge was dropped after police came forward with no evidence.