He sticks it into a USB port in his tablet. When it lights up, you touch the fingerprint sensor on the upper surface. Bingo. Your identity is verified by biometrics. Also, all of your information is accessed through various databases. You do have a valid driver's license, your insurance is up-to-date, and you do own the vehicle that you are driving. To make sure, the cop scans the RFID chip in the vehicle, and the VIN number checks out with the information in your USB identity device.
Gone are the days when ID can be faked on a piece of paper. It is going to cost you some real coin in hardware, programming and engineering if you want fake ID. This same device will be used to verify that you are of the legal drinking age in bars, and that you have a certificate to possess medical marijuana.
The best thing about this electronic ID, is that it will save the states, especially California, millions in photo id. Everytime someone has a facelift, liposuction, collagen injection, brow lift, nose job or whatever, they don't look like their photo id any more. Their fingerprints will never change.