We Can Tell You That You Can't Fly; We Can't Tell You Why

"Last spring the Department of Homeland Security began telling travelers barred from flying whether they were on the list and, if so, informing them of their right to initiate a "redress inquiry." But it's hard to get off the list if you don't know why you were put there to begin with, and the government says it can't be specific because that would endanger national security."