First of all the statement DOT APPROVED is misleading. NHTSA, an arm of the U.S. DOT, does not approve or disapprove MV equipment. It does set Federal Motor Vehicle Safety Standards for all MV equipment. FMVSS 108 covers lights. Manufacturers SELF-CERTIFY that their product meets the standard.
Several years ago when the aftermarket tail light/lens first became popular, there were many versions and most of them did not comply with FMVSS 108 even though the packaging said legal in 50 states or DOT approved. The products also have DOT numbers imprinted on them. These letters/numbers indicate certain parts of the product are compliant such as rear lens, rear color, rear reflector, side reflector, side lens, side color etc. There were DOT numbers on many of these aftermarket lenses but usually all of the numbers were not present. This indicates that parts of the lens were not compliant. Also see http://fmvss108.tripod.com-this
is a NON-government site with lots of info about lights-mostly taillights.
HID headlights-If it has a transformer (ballast) it is an HID light. A true HID light casts a white light (looks like light blue tint). There are cheap imitations which are a plain bulb with a blue coating and these cast a blue light. When I stop a car with suspect headlights I hold a piece of white paper in front of the light. If the paper turns blue, that is illegal and driver gets "Norked" (gets a ticket). See the following NHTSA Interp letter at http://www.nhtsa.dot.gov/cars/rules/...18.ztv.html-It
says, "SAE J578c defines white by blue, yellow, green, red and purple boundaries within a chromaticity diagram. Thus, it is possible to design a headlamp that emits a light that approaches the blue boundary and is perceived as having a blue tint but which nevertheless remains within the boundaries that define "white"".
As far as what state you live in it does not matter. All states light laws follow FMVSS 108 for the basic MV lights.
I AM NOT SUGGESTING THAT YOU ARGUE WITH ANY POLICE OFFICER WHO MAY STOP YOU FOR THE HEADLIGHTS. You could try carrying a copy of the above NHTSA interp letter with you and politely asking to officer to read the above paragraph (this could backfire). Best bet is to plead not guilty and plead your case at court.
Hope this answers your question.