Computer-Assisted Passenger Screening System (CAPS)

Probability theory put to good use:
Carnival Booth: An Algorithm for Defeating the Computer-Assisted Passenger Screening System

"To improve the efficiency of airport security screening, the FAA deployed the Computer Assisted Passenger Screening system (CAPS) in 1999. CAPS attempts to identify potential terrorists through the use of profiles so that security personnel can focus the bulk of their attention on high-risk individuals. In this paper, we show that since CAPS uses profiles to select passengers for increased scrutiny, it is actually less secure than systems that employ random searches."

It is an interesting read for people who like to see good old mathematics crush political arguments or for those that never thought about it.

For those who think these and other (in)security measures (such as secret laws) would never be misused, think again - US senator Edward Kennedy's (Democrat) adventure.
Implications? Civil Liberties? Freedom of Movement? Freedom of Speech? I won't even mention privacy - no one seems to care about it anymore.