According to the Wall Street Journal, “Federal agents have persuaded police officers to scan license plates to gather information about gun-show customers, government emails show, raising questions about how officials monitor constitutionally protected activity.”

The activity revealed in the emails suggests that the known incidents are limited to border control and occurred in California in 2010.

The WSJ continues:

Emails reviewed by The Wall Street Journal show agents with the Immigration and Customs Enforcement agency crafted a plan in 2010 to use license-plate readers—devices that record the plate numbers of all passing cars—at gun shows in Southern California, including one in Del Mar, not far from the Mexican border.

Agents then compared that information to cars that crossed the border, hoping to find gun smugglers, according to the documents and interviews with law-enforcement officials with knowledge of the operation.

The investigative tactic concerns privacy and guns-rights advocates, who call it an invasion of privacy. The law-enforcement officials say it is an important and legal tool for pursuing dangerous, hard-to-track illegal activity.

There is no indication the gun-show surveillance led to any arrests or investigative leads, but the officials didn’t rule out that such surveillance may have happened elsewhere. The agency has no written policy on its use of license-plate readers and could engage in similar surveillance in the future, they said.

This is not the only federal agency, however, that has considered scanning the license plates of gun show attendees.

The ACLU reported at the time:

The Drug Enforcement Administration and the Bureau of Alcohol, Tobacco, Firearms and Explosives collaborated on plans to monitor gun show attendees using automatic license plate readers, according to a newly disclosed DEA email obtained by the ACLU through the Freedom of Information Act.

The April 2009 email states that “DEA Phoenix Division Office is working closely with ATF on attacking the guns going to [redacted] and the gun shows, to include programs/operation with LPRs at the gun shows.” The government redacted the rest of the email, but when we received this document we concluded that these agencies used license plate readers to collect information about law-abiding citizens attending gun shows. An automatic license plate reader cannot distinguish between people transporting illegal guns and those transporting legal guns, or no guns at all; it only documents the presence of any car driving to the event. Mere attendance at a gun show, it appeared, would have been enough to have one’s presence noted in a DEA database.

Responding to inquiries about the document, the DEA said that the monitoring of gun shows was merely a proposal and was never implemented.

Additionally, the ATF was allegedly planning to work with the DEA to scan and record the license plates of gun show attendees.  This plan, however, was also reportedly scrapped.

According to Fox News, “Erich Pratt, executive director of Gun Owners of America, said his group also opposes such surveillance. “Information on law-abiding gun owners ends up getting recorded, stored, and registered, which is a violation of the 1986 Firearm Owners Protection Act and of the Second Amendment.”

Scanning gun show attendees’ license plates is a plan that federal agencies continue to revive and revise.