The Florida Highway Patrol is the defendant in an interesting class action by Eric Campbell, who was ticketed for warning other drivers of a speed trap. Drivers will sometimes flash their lights to warn approaching cars in the opposite lane of the speed trap. However, the Florida Highway Patrol insists that that is illegal and gave Campbell a ticket for improper use of high beams.
The ticket was issued under “Florida Statue 316.2397.” Presumably, the officer was thinking of subsection 7:
(7) Flashing lights are prohibited on vehicles except as a means of indicating a right or left turn, to change lanes, or to indicate that the vehicle is lawfully stopped or disabled upon the highway or except that the lamps authorized in subsections (1), (2), (3), (4), and (9) and s. 316.235(5) are permitted to flash.
Notably, flashing lights does not necessary cover putting on your highbeams as a warning. Indeed, flashing lights could refer to the automatic flashers such as the emergency lights as opposed to the headlights.
One of the more interesting things for American drivers in France is the law that the police have to warn drivers of speed traps. Before any speed camera, there are signs warning you that you are approaching one. The result is that all of the cars slow down but few people get tickets. You got to love France.