WASHINGTON - US police departments are rapidly expanding the use of automatic license plate readers, sparking debate on whether the technology is a valuable crime-fighting tool or a massive invasion of privacy.
A recent report by the American Civil Liberties Union (ACLU) warned that these readers -- used in patrol cars or fixed locations on streets and highways -- collect data on tens of millions of Americans who have committed no wrongdoing, with a potential for privacy abuses.
The devices scan license plate numbers and match these against databases to help police locate stolen cars, criminals or missing children. Backers say this can free police officers from a monotonous task and help solve crimes.
But with many Americans uneasy over government surveillance of the Internet, the expansion of this technology has sparked concerns about Big Brother.
"In our society, it's a core principle that the government doesn't watch people's innocent activities just in case they may connected with a crime," said Allie Bohm of the ACLU.
"In many cases, police are retaining this data indefinitely with few privacy protections. The tracking of people is an invasion of privacy. It can reveal people's political views, religious activities and a lot of other personal information."
The ACLU report, based on a survey of hundreds of US police departments, said almost three quarters of police agencies reported using license plate readers, and 85 per cent planned to increase their use.
Only a tiny fraction of the license plate scans helped point to crimes or stolen vehicles, according to the ACLU survey.