Science often follows fiction and a new program called Future Attribute Screening Technology (FAST) which was created by US Department of Homeland Security is about to start field testing, according to Sharon Weinberger at Nature. It's intent is to be "Minority Report", without the 1950s mutants, and to stop terrorism
When optimized, it wants to be able to spot terrorists by using non-contact sensors (so, from a distance) that will analyze irregular physiological factors like heart rate to determine who is about to commit a crime.
How can that be field tested? In the lab, they calibrated it by having people carry out a "disruptive act" and measuring their physical behavior, but not all terrorists will have a higher heartbeat or sweat more or have shifty eyes because not all terrorists are nervous. If you shoot a deer, and you have never shot a deer or fired a gun, your heart rate will go up and you will worry about the recoil of the gun and the noise and likely will flinch when you pull trigger - if I shoot a deer, I just shoot a deer.(1) To a terrorist who has been crafty enough to get into the US, you are the deer.
Is there really a default signature for 'intent' such a machine could use? Inexperienced international travelers get nervous even going through customs at an airport. An experienced custom official can look at a passport and see someone has not traveled much and recognize a passenger is nervous about the unknown, not about committing a criminal act.
They claim "FAST uses an established independent peer-review process to ensure objectivity and thoroughness in addressing all aspects of the program" but they aren't disclosing how reviewers are chosen any more than Nature is - yet Nature is selling magazines, not arresting people.
Success rate so far: only around 70%. That could be a lot of false positives. Obviously they are field testing to try and make the technology more reliable but they aren't disclosing where testing is happening; precognition of crimes is one area where conservative groups and the ACLU will be together on protesting the encroachment of the government in establishing motivation.
More: Privacy Impact Assessment for the Future Attribute Screening Technology (FAST) Project
(1) Then I call one of my brothers and tell him my back hurts and schmooze him into gutting it and dragging it down the mountain.