Since this is a Civic forum, then yes, PIAA's blue bulbs are technically illegal. Why? H4 is a motorcycle headlight bulb designation...basically a 9003 bulb.

Stick with FMVSS108-compliant bulbs such as Sylvania Cool Blue and Silverstar, GE Super Blue, Wagner LazerBlue, etc.

The blue describes the bulb, not the light color, as the color is whiter than stock.

http://lighting.mbz.org

Basically, the bulb has to be marked with DOT and 9003.

Anyways, as long as your light bulb is white and not obviously blue, you should be okay.