A growing body of anecdotal evidence suggests that automatic license-plate readers help solve crime and apprehend felons, but the proliferating technology raises privacy concerns, says the Columbus Dispatch. The readers began appearing in central Ohio police cars and were affixed to freeway infrastructure about eight years ago. The State Highway Patrol, Columbus police and Franklin County sheriff's office all use readers, as do many smaller departments. A car equipped with a reader can scan thousands of plates each day.
Software then compares the plate numbers with those on law-enforcement “hot lists.” Agencies keep the digital pile of collected numbers for varying lengths of time, and they can be picked through retroactively by police looking for a particular plate. It is the warehousing of aggregate plate information that most worries groups such as the ACLU, because the bulk of the collected numbers undoubtedly belong to law-abiding citizens. An ACLU of Ohio official said the group objects “when all of us are watched by the government simply because the technology exists for them to do so.”