brain-based lie-detection technology

Imagine a world of streets lined with video cameras that alert authorities to any suspicious activity. A world where police officers can read the minds of potential criminals and arrest them before they commit any crimes. A world in which a suspect who lies under questioning gets nabbed immediately because his brain has given him away. Though that may sound a lot like the plot of the 2002 movie "Minority Report," starring Tom Cruise and based on a Philip K. Dick novel, I'm not talking about science fiction here; it turns out we're not so far away from that world. But does it sound like a very safe place, or a very scary one?