I don't think you understand the law. The cirmcumstance about an American citizen wouldn't arise unless he was picked up for a suspected crime. And then his information would be run through a federal data base, which would confirm he was an american citizen.
Read this by one of the principal drafers of the AZ bill, someone I know personally and respect and admire: KOBACH: Arizona acts as Washington dithers
"Myth No. 1: The law requires aliens to carry identification that they weren't already required to carry. On the contrary, the law simply penalizes aliens who fail to carry the registration documents that federal law already requires them to keep on their person. These federal crimes (8 United States Code Section 1304(a) or 1306(e)) have been around since 1940. The Arizona law simply adds a layer of state penalty to what already was a crime under federal law.
Ironically, the open-borders crowd has for years insisted that we use the term "undocumented" when referring to illegal aliens. Now, when a state takes seriously the documentation requirements of federal law, that crowd becomes apoplectic.
As for U.S. citizens, the law does not require them to carry any identification whatsoever. Indeed, the law cannot possibly be applied against U.S. citizens; only an alien can be found guilty under the Arizona statute."
I wasnt trying to be critical, non-citizens are already required to carry ID as a green card but citizens are not which makes the law more difficult to really use effectively(I understand that this law will help police as it is but it could work better.) .
There was a time not long ago when police pulled americans over and asked for ID and could arrest you if you didnt have one. Maryland encodes your birth date on the bar code of your drivers licence. AZ could encode an immigration status on a similar ID (drivers licences should already be good given federal law.)
On the other side I have reservations about a national ID as a requirement to work or anything else. The reason is the federal government already punished citizens by revoking their passport over child support payments (a family court issue.) States do the same with drivers licences, ability to drive, but that is the state.
We do not want the federal government with that much power over those they can effectively demonize.
The Federal law:
***********Every alien, eighteen years of age and over, shall at all times
carry with him and have in his personal possession any certificate
of alien registration or alien registration receipt card issued to
him pursuant to subsection (d) of this section. Any alien who fails
to comply with the provisions of this subsection shall be guilty of
a misdemeanor and shall upon conviction for each offense be fined
not to exceed $100 or be imprisoned not more than thirty days, or both
http://www.freerepublic.com/focus/news/2502120/posts?page=17#17