This post by ABFH got me thinking about all the ways in which the climate of suspicion that prevails in post-9/11 America (and in police/surveillance states in general) tends to single out those who differ in some way from social and cultural norms for scrutiny, harrassment and disenfranchisement. People of color, immigrants, foreign nationals (especially those from non-European countries), youth, members of religious, cultural, ethnic or linguistic minorities, people with disabilities or mental illnesses, civil libertarians and left-wing political activists are the canaries in the coal mine when it comes to civil-rights violations; as the margins of society are slowly pared down closer to the core, all it will take to flag a person as suspicious may be a left-of-center voting record, unorthodox books checked out on a library card, donations to the wrong charities, or even buying habits that don't match the typical pattern for your demographic. (Make $100,000 a year and haven't bought a new car? Why not? You're not planning to blow yourself up, are you??)
I've mentioned previously how the TSA's methods of screening for terrorists using subtle behavioral cues would also implicate many disabled, mentally ill or simply stressed-out air travelers with no criminal intent whatsoever. Proposals for requiring voter identification at the polls, which are ostensibly to prevent fraud but would have the effect of screening out voters without proper identification, like those without driver's licenses (disproportionately elderly, poor or disabled) or birth certificates (disproportionately elderly and black), constitute another example of how difference can be criminalized.
The last piece of the puzzle I want to address is the use of personal data of the type I listed in the first paragraph --- travel history, TV viewing habits, movie rentals, online purchases, library checkouts --- to create electronic dossiers on every American for whom such data exist. Since no one owns these data, anyone with the power to dig them up and analyze them (which, given the processing power needed to do that for any appreciable number of people, limits that pool to fairly large corporations and the government) can do so.
According to the "Talk of the Nation" segment linked above, those tools are mostly being used by corporations (and political candidates --- they're selling something, too) to develop precision-targeted advertising, but there was a brief mention of counterterrorism applications as well. Specifically, agents would be combing through those banks of personal data looking for anything "suspicious." An example that had actually been considered (although scrapped) was to track falafel consumption nationwide, and boost surveillance of areas where the rate rose sharply!
As silly as that sounds, there are serious implications to it. If the general MO is going to be tracking innocuous cultural markers like food, reading and media consumption, that sets the stage for Fahrenheit 451-style policing of culture. Indeed, it's already happening a bit; among those detained at Guantanamo Bay are a number of scholars of Islam whose areas of study flagged them as potential terrorists. The technology doesn't distinguish between an Islamic scholar researching a book on, say, the theological underpinnings and historical context of Wahhabism and an al-Qaeda recruit reading Wahhabi texts to psych himself up for a suicide bombing. In the eyes of the surveillance state, all contact with the Forbidden Other is equally suspect.
This is why a surveillance state can't handle human diversity. If the goal is to be able to tell, at a glance, which individuals in a large, ever-changing crowd might make trouble, the ideal scenario is one in which law-abiding citizens all look one way and terrorists all look another way.