If the later, then I can understand why people are against requiring such an arbitrary form of identification.
A bored immigration guy in Detroit once amused himself by pointing out that neither my driver's license nor my draft card showed that I was in fact a citizen of the US, or I guess a legal resident. When I said that this was the only ID I was carrying, and shrugged, he waved me through.
Varies from State to State as far as know. At least in some states it's enough to prove that you live in the state, not that you are living there legally.
https://en.wikipedia.org/wiki/REAL_ID_Act
I definitely had to show the 4 types of documents the last couple of times I've moved (photo/birth/status/address). Stupidly, the first id that was obtained by showing that stuff didn't serve as proof of the first 3 when I moved again.