“One would think that agents charged with protecting us from "dirty nukes" would enjoy the same discretionary search authority as patrolman who make traffic stops. In fact, they have less. If a patrolman pulls you over for weaving between lanes, and smells bourbon on your breath, he does not need a warrant to give you a breath test. But if an FBI agent learns that you are a member of a known terrorist group, and that you behaved suspiciously at a flight school, he must jump through bureaucratic hoops of fire to search your laptop computer.”