[MrEdd]

But how does law enforcement distinguish between the latter and law-abiding citizens who neither have green cards nor are breaking the law?

They run a computer check on your driver's licence or state ID which you must have to write checs or get a bank account. Or on your social security card.

All of that information is in their data base.

[DrC]

“They run a computer check on your driver’s licence or state ID which you must have to write checs or get a bank account. Or on your social security card.”

Thanks, this is helpful. But what if I’m a legal citizen walking down the street without any of these documents? Can they run the check on my self-declared SSN? If so, what’s to prevent an illegal from reporting a stolen SSN and matching name? If not, does that mean any American who fails to carry identification is subject to arrest at any time?