It's a very grey area that hasn't gone to court lately, if I recall. Throw HID's in the wrong housing and you're gonna get stopped for being a hazard and absolutely blinding everyone. Go to strong on them and you're likely to get a cop saying that the really blue or purple tint violates our law against colored headlights. As  long as your housings are correct, DOT approved, and you run about 4-6k kelvin HID's you're fine.

*disclaimer, this is not legal advice, I am not a lawyer, I will not bail you out of jail

Throw HID's in the wrong housing and you're gonna get stopped for being a hazard and absolutely blinding everyone.

I almost ordered a conversion kit(They were the white lights with a slight tint of blue in them.), but at the last minute I cancelled it due to that reason. I didn't know if my stock housing was able to handle them so I didn't want to risk spending over $200 on something just so I can glare that shit out of people. The other reason is my wiring, due to HID's being brighter and a different setup, then my wiring might not be able to handle them unless I replace it.

Now on Thursday I'm simply going to get light bulbs which are brighter and produce a similar white light.