Sun Microsystems millionaire John Gilmore is suing the Justice Department because it has secret laws requiring people to show ID when flying on a commercial domestic plane. Here's a good Reason article about it.
But as Gilmore has argued, real security doesn't often have a great deal to do with knowing who someone is, or who a card says he or she is. (Even the most biometrically sophisticated of modern ID documents will be potentially forgeable for those with a strong incentive to do so.) Real security has much more to do, in Gilmore's airline context, with making sure people, whatever their card says, don't bring weapons or bombs on planes—or making sure that trustworthy people on planes, whether pilots or air marshals, are empowered to resist miscreants. (After 9/11, normal citizens have almost certainly gotten the message to resist at all costs.) The government still doesn't want to allow the good guys to defend themselves on planes effectively, and thus are all the more insistent on the security theater of showing an ID card.Link