In the state of Michigan's vehicle code is this snippette:
Unless both covered and unlit, a vehicle driven on the highways of this state shall not be equipped with a lamp or a part designed to be a reflector unless expressly required or permitted by this chapter or that meets the standards prescribed in 49 C.F.R. 571.108.

And this is the opinion of the state attorney general " The Michigan Vehicle Code provides that a vehicle driven on Michigan highways may not have a lamp or a reflector unless it is: 1) expressly required by Chapter VI of the Michigan Vehicle Code; 2) expressly permitted by Chapter VI of the Michigan Vehicle Code; or 3) meets the standards prescribed in 49 C.F.R. 571.108. Other lamps or reflectors can only be on a moving vehicle if they are both covered and unlit. Therefore, it is unlawful for a vehicle to have neon ground effects lighting unless the neon tubes are both covered and unlit while the vehicle is driven on the highways of this state."

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