Are HID headlights in California illegal?

I'm thinking about putting aftermarket headlight bulbs with 5000K (whitish-blue) HID lights on my Honda Civic.It will be done by a tuning shop, which will provide me the service and kit to install.

I want to know if this process is illegal in California only.

Any conversion that meets US DOT requirements meets All state requirements in All states.

If you're planning on putting them in the factory headlight assemblies, then no, it's not legal. Not in CA, not anywhere in the US The factory headlight assemblies are only certified for halogen bulbs. HID bulbs have a different focal point so the reflectors actually cast less of the light onto the road. Plus, HIDs run hotter and have been know to melt or at least distort the lens. Either buy HID certified headlight assemblies or skip the conversion. You won't be happy with HIDs in halogen headlghts.