The new social surveillance can be defined as scrutiny through the use of technical means to extract or create personal or group data, whether from individuals or contexts. Examples include: video cameras; computer matching, profiling and data mining; work, computer and electronic location monitoring; biometrics; DNA analysis; drug tests; brain scans for lie detection; various forms of imaging to reveal what is behind walls and enclosures. There are two problems with the new surveillance technologies. One is that they don't work and the other is that they work too well. If the first, they fail to prevent disasters, bring miscarriages of justice, and waste resources. If the second, they can further inequality and invidious social categorization; they chill liberty. These twin threats are part of the enduring paradox of democratic government that must be strong enough to maintain reasonable order, but not so strong as to become undemocratic.