If someone develops a practical mind-reading device, you can expect the Department of Homeland Security to argue that skulls are merely another 'closed container' that officers guarding the border may search at will. After all, government agents have long been allowed to read documents in briefcases carried by Americans returning from abroad. Why should the medium in which information is stored make a constitutional difference?

That argument is only slightly more far-fetched than the one DHS uses to justify its policy regarding border searches of laptop computers. Given the nature and quantity of the data they contain, portable computers are in many ways extensions of our brains. Yet DHS is treating them as if they were no different from purses or fruitcake tins. ....