Do you know what's under all of that Hair?
Rules About Wearing Islamic Clothing in ID Photos
It has come up before in Florida (at least) and the woman had her license revoked when she refused to retake her ID photo without the hijab on. She lost at least the first case in court.
LiveLeak.com - ACLU Supports Burkas And Veils In Photo ID's.
I believe the normal procedure is to simply have the photo taken in a different room, where only a female employee can see the woman's face. If an officer were to arrest a woman wearing a hijab/burqa/veil then she would still be eventually expected to show her face, even if it is only to a female officer.
"A woman is like a teabag, you never know how strong she is until she gets in hot water." - Eleanor Roosevelt
Keep your religion out of other people's marriages.