LTO regulations limit it to two units mounted at the same level or below the level of the oem headlamps (since this was drafted when euro cars had foglamps built into their headlamp housings).

Again, these regulations were made way before LED tech became commonplace.

I have one on the responder unit (Medical Control 1) but limit its use to roads with no oncoming traffic or if the vehicle in front and traveling in the same direction is 350 or more feet away.

We also use it for scene lighting when we work.