For years, police agencies around the country have deployed automated license plate reader cameras (ALPR, also known as ANPR) without seeking public input or approval. Often the federal government picks up the tab for the cameras in the form of homeland security grants that support an effort to centralize a repository of the driving histories of motorists. The scope of the effort has inspired a legislative backlash.

State lawmakers in Florida, Indiana, Missouri, Montana, New Jersey, Vermont and Virginia are contemplating measures that range from mild restrictions on the practice to outright bans on the scanning technology.

In Virginia, state police were caught using ALPR to spy on attendees at political rallies on the Republican and Democratic presidential ticket in 2008. As a result, lawmakers have advanced a mild set of restrictions. Senate Bill 965, if enacted, would allow police agencies to preserve license plate data for up to seven days in relation to a criminal investigation, but they would have to obtain a warrant to preserve the data beyond seven days. Earlier this month the state Senate gave unanimous approval to the measure. A state House committee approved the bill on a 17 to 4 vote on Friday.

Montana state lawmakers are taking a firmer stance, banning license plate readers with exceptions weigh station cameras and cameras used by meter maids to issue parking tickets. City officials could also use cameras for "planning" purposes, but no personally identifiable information could be stored when used for that purpose without a warrant. House Bill 344 passed the state House Judiciary Committee on Friday.

The Tenth Amendment Center has been encouraging states to take action on ALPR restrictions in order to cut off the ability of federal agencies to add information to a nationwide motorist tracking databases.

"No ALPR data means no license plate tracking program," the group's spokesman, Mike Maharrey, said. "More importantly, this limits government power and advances liberty on both the state and national level."

The Florida, Indiana, Missouri, New Jersey and Vermont legislatures have not taken action on the license plate camera legislation that has been introduced.