Theoretically the barcode on the back calls to the DOT database and if there's a record matching it comes back as valid, if not it comes back as fake. Where I live it just says "yes there's a match" it doesn't pull up any further information due to privacy laws. Obviously the way around that is to just copy a valid barcode, but I would hope any mass use of the same barcode would be flagged.

In reality it does little to nothing.