In Western Australia it is a traffic infringement to mount a ‘light bar’ above the level of the engine bonnet. Like ‘spotlights’, it also a requirement that light bars be included in the light-dip circuit so that when your headlights are dipped the light bar(s) extinguish.
This is the same for spotlights.
Up until now the WA Police have not been too worried about enforcing this traffic rule.
Spotlights and light bars mounted above the engine bonnet can result in a ‘yellow sticker’, which indicates your car is roadworthy—unless you have a permit to mount them on your roof (which can be obtained for farm vehicles, and the like).
As from the 1st of Decemeber the WA Police are planning to upgrade their policing of the light bar mounting rules.
Having encountered light bars switched on coming towards me a number of times when I was going back and forth to Collie for my old job, I can well understand why this rules exists. Especially the requirement that the light bars be included in the light-dip circuit. You see the oncoming car dip their headlights but their frigging light bar remains on. Then they suddenly realise the light bar is still on and switch it off. But by then you are basically blinded and almost need to pull off to the side of the road.