The heads of the Senate Judiciary Committee this week challenged Big Brother with the latest in a series of letters to the Obama administration questioning controversial new methods for domestic surveillance.

On Wednesday, Sens. Charles Grassley (R-Iowa) and Patrick Leahy (D-Vt.) wrote to Attorney General Eric Holder and raised concerns about the Drug Enforcement Agency’s use of a license-plate tracking system that helps monitor vehicle movements in real time.

The DEA’s database includes hundreds of millions of drivers, and the agency has pushed to expand the program nationwide after launching it along the Southwest border region, according to a Wall Street Journal report on Monday.


A license-plate reader mounted on a police vehicle in Washington, D.C. (Paul J. Richards/AFP/Getty Images)

Grassley and Leahy also wrote to Holder last week raising concerns about the Justice Department’s use of radar technology to detect movement inside buildings, including private citizens’ homes.

And in a letter to the attorney general last month, the senators questioned DOJ’s use of devices known as “Stingrays” and “dirtboxs,” which mimic cell-phone towers to collect data from cellular devices in their vicinity.

“We appreciate that all of these new technologies are potentially useful law-enforcement tools,” the lawmakers said in their letter this week. “But we remain concerned that government programs that track citizens’ movements, see inside homes, and collect data from the phones of innocent Americans can raise serious privacy concerns.”

Grassley and Leahy have asked the Justice Department to brief the Senate Judiciary Committee on the three surveillance programs by mid-February.

The senators’ concerns echo those of privacy advocates, who have criticized the Obama administration for moving forward with new domestic-surveillance programs without keeping the public informed or providing details about accountability.

“People might disagree about exactly how we should use such powerful surveillance technolgies, but it should be democratically decided, it shouldn’t be done in secret,” American Civil Liberties Union policy analyst Jay Stanley told the Journal.

DOJ has defended its license-plate tracking program, telling the Journal that its goals are nothing unusual. “It is not new that the DEA uses the license-plate reader program to arrest criminals and stop the flow of drugs in areas of high trafficking intensity,” a spokesman said at the time.

In a separate Journal article, the Justice Department declined to discuss the possibility of using devices that mimic cell towers, saying the matter could help criminal and foreign powers to learn about U.S. surveillance capabilities. However, the official said that the department complies with federal law and seeks court approval for surveillance whenever necessary.

The initial goal of the DEA’s license-tracking system was to seize assets such as cars and cash from drug traffickers, but the government has expanded it to monitor vehicles associated with other crimes such as kidnapping, murder and rape, according to the Journal article.

The practice of seizing assets has become highly controversial in recent years, largely because law-enforcement agencies sometimes take assets without evidence of a crime, and because police use the money to purchase big-ticket items such as armored vehicles and additional surveillance equipment.

RELATED: Check out The Post’s “Stop and Seize” series for more on this topic

Grassley and Leahy said in their letter that the civil-asset forfeiture program “needs greater transparency and oversight,” including with any efforts to expand it through license tracking.

Holder this month took action to prohibit local and state police from using federal law to justify asset seizures without warrants or criminal charges.

The senators’ letters came less than a year after the Department of Homeland Security canceled plans to develop a national license-plate tracking system amid concerns from privacy advocates.

RELATED: Department of Homeland Security cancels national license-plate tracking plan