I believe it is the inevitable outcome of the &quot;Internet of Things&quot; meets the &quot;identification of things&quot;. Today a number of police departments have red light cameras the give no tickets. So you might wonder why they are still there. As it turns out they do an excellent job of watching your license plate go through an intersection and recording that on a server. Add that to police cars with their own license plate readers and GPS and you end up with a cloud of data points, with time and GPS information for places in a city where a license plate has appeared.<p>That provides a very valuable database for law enforcement, if you know a car was used during a robbery, poof you know where that car as been, so you are one up on the robbers. Even if the license plate was stolen or the car stolen, you have it from the point the plate was stolen to the present. The ALCU has been trying to get statements about how long this data is kept and how it is accessed.<p>Today you can recognize faces with machines better than you can with humans. A camera can take pictures and store the face data with no other personally identifiable information, and yet when you suspect someone of something you plug in their face data and &quot;poof&quot; you get all the cameras that have seen them and when. Recent laws about trying to protect this sort of abuse not withstanding. [3]<p>IMSI catchers and simply Wifi MAC address catchers for the purposes of advertising (or surveillance)[4] can provide GPS + Time + identifiable number logs.<p>Storage is cheap, 32 bit CPU chips are free, HD cameras are cheap, and software radios can build white-space mesh networks on demand. When you lay a grid of these passive technologies around town, it will become the most powerful tool humans have ever invented for keeping track of, or locating, other humans of interest.<p>The fun part is that private citzens can play too, anyone can put together a fleet of cameras recognizing faces and license plates with a Raspberry Pi 2. And if you have a HackRF One you can pick up GSM bands and WiFi bands to note the phones, tablets, laptops nearby. Call it $400&#x2F;unit, $40,000 for 100 units (two at every intersection would cover an area of 7 square blocks. Not something you would do on a lark but certainly within reach of someone who could profit from the information.<p>[1] <a href="http:&#x2F;&#x2F;www.kake.com&#x2F;home&#x2F;headlines&#x2F;Salina-police-using-license-plate-readers-to-solve-crime-332972161.html" rel="nofollow">http:&#x2F;&#x2F;www.kake.com&#x2F;home&#x2F;headlines&#x2F;Salina-police-using-licen...</a><p>[2]  <a href="http:&#x2F;&#x2F;www.governing.com&#x2F;news&#x2F;state&#x2F;sl-surveillance-cameras-key-to-crime-solving.html" rel="nofollow">http:&#x2F;&#x2F;www.governing.com&#x2F;news&#x2F;state&#x2F;sl-surveillance-cameras-...</a><p>[3] <a href="http:&#x2F;&#x2F;www.law360.com&#x2F;articles&#x2F;742169&#x2F;shutterfly-can-t-shake-biometric-data-privacy-suit" rel="nofollow">http:&#x2F;&#x2F;www.law360.com&#x2F;articles&#x2F;742169&#x2F;shutterfly-can-t-shake...</a><p>[4] <a href="http:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;technology-23665490" rel="nofollow">http:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;technology-23665490</a>