Meet the company that wants to scan your license plate for the police

License-plate readers that scan passing cars and instantly match them to criminal databases have moved quickly from sci-fi concept to daily reality, even in small towns. And just as quickly, privacy advocates have raised concerns about the systems, asking who has access, how long the data gets stored and what other kind of limits law enforcement should face for their use.

But one private firm that's building its own database of license plate snapshots has started pushing back against such concerns, lobbying against bills that would limit its business and successfully rolling back some limits after arguing it had a First Amendment right to photograph cars.

Earlier this week, Vigilant Solutions released a poll of California residents it had commissioned backing its efforts to stop a bill in the state legislature which would limit license-plate readers. Company founder and chief executive Shawn Smith called the technology "a critical tool that has helped law enforcement solve thousands of violent crimes and enabled insurance and financial services companies to repossess stolen and delinquent vehicles."

Most law enforcement agenices would agree. Most police departments have automatic plate readers mounted on patrol vehicles, while many used fixed versions that look like speed cameras which can record and read thousands of plates a minute. Earlier this month, Kansas City police arrested a man suspected of shooting at some 13 vehicles on local freeways, with several injuries but no deaths. The big break in the case came in part from license-plate reader data; after a woman reported the license plate of a mysterious car, police were able to establish the suspect's home, movements and see where his car had been in the past.

But some studies, including one by the American Civil Liberties Union, have found that such cases are rare, with the scanning only resulting in some kind of charge 0.3 percent of the time; most of those are for traffic infractions like driving with a suspended license. The ACLU says without strict guidelines on how long and how much data is stored, the system can be abused; it found one case where a county sheriff's department tracked everyone who went to "a rave party and a concert at a country-western bar."