From VOA Learning English, this is the Technology Report.

Law enforcement agencies across the United States are using cameras to take pictures of automobile license plates. The idea is to build a computerised collection of information detailing the daily travel of millions of Americans.

Arlington County Police Detective Mohammed Tabibi is with the Automobile Theft Department. He uses a license plate readers, also known as a LPR to look for stolen vehicles.

"It has paid dividends. We have caught some people involved in some serious crimes because of the LPR," said Tabibi.

The use of LPRs is growing across the United States. Some are secured to poles along roadsides, others are placed in law-enforcement vehicle. Privacy groups are concerned about the growing use of these devices. They say the information collected is stored on computers and shared with other local, state and federal law enforcement agencies.

Jay Stanley is with the American Civil Liberties Union(ACLU).

"What they are also doing is storing everybody's time, place, and location. And many police departments are holding that information indefinitely. You know in our society, the government doesn't follow you and invade your privacy and track you unless it has a specific reason that you are involved in wrongdoing," said Stanley.

Until recently, Kevin Rearden served as Captain of the Arlington county Police, he also headed the county's Homeland Security Department before he retired. Mr Rearden said, county policy calls for the LPR information to be kept for six months.

"We originally had a two-month period, and the detectives requested the chief extend it to six months because they found in so many investigations, keeping it for two months wasn't long enough," said Rearden.

But he said, other law enforcement agencies that use the county's information may store it for unlimited periods of time.

Supporters of privacy rights say they have no problem with police departments taking pictures of license plates to investigate crimes. But Jay Stanley says, they're against storing the information for long periods of time.

"...Once you are past a certain periods of time, it is very unlikely it is going to be useful. Meanwhile we are creating this giant infrastructure for tracking everybody all the time," said Stanley.

Retired Arlington country Captain Rearden disagrees.

"They keep bringing up the word tracking. And if I went out and ran your tag in our server, I would not be able to track you. I would be lucky if I could put [you in] a few places in Arlington in a particular time. By no stretch of the imagination would I be able to track you," said Rearden.

The ACLU says Americans need to know how federal officials are using the information collected from LPR cameras, the group has brought federal charges against the Department of Justice and the Department of Homeland Security.

And that's the Technology Report from VOA Learning English. I'm Milagros Ardin.