After the Department of Homeland Security canceled a plan for broad law enforcement access to a national license-plate tracking system in February, officials established a policy that required similar plans be vetted by department privacy officers to ensure they do not violate Americans’ civil liberties.

Two months later, however, officials with DHS’s Immigration and Customs Enforcement agency bypassed the privacy office in purchasing a one-year subscription for a commercially run national database for its Newark field office, according to public contract data and department officials. In June, ICE breached the policy again by approving a similar subscription for its Houston field office. The database contains more than 2.5 billion records.

The policy was created after Homeland Security Secretary Jeh Johnson, who oversees ICE, canceled a solicitation that could have given ICE field offices across the country — more than 12,000 personnel — access to a national license-plate database.

That solicitation had prompted a backlash from privacy advocates who have raised concerns that the information can be abused to track the past and current movements of ordinary citizens who are under no criminal suspicion. Advocates said the failure to follow procedures fits a pattern in which concerns over privacy are overlooked as law enforcement officials clamor for subscriptions to massive license-plate tracking databases.

Officials at ICE say the field office use is limited, involves ongoing criminal investigations for which they had earlier access to the database, and is not related to civil immigration enforcement. They said the breach of the new policy was inadvertent and a result of a miscategorization of the contracts.

The commercial databases draw information from readers that scan the tags of every vehicle crossing their paths. Records, for instance, can be obtained from repossession companies, whose drivers mount cameras on their cars and capture images of license plates of passing or parked cars, along with the time and location of the photo.

For federal officials, the information has become a critical tool to help the agency locate suspects who could pose a threat to public safety. But they acknowledged that they have not imposed privacy safeguards on use of the database, such as rules limiting how long the data agents look at may be kept.

In a statement, ICE spokeswoman Gillian Christensen said over the past six months, the agency, its privacy office and the DHS Office for Civil Rights and Civil Liberties have been reviewing ICE’s practices and policies governing the use of license-plate-reader databases. Officials said a privacy impact assessment is being prepared.

Christensen added that agency attorneys in 2012 concluded there were no legal obstacles “with respect to privacy and data retention laws” to using the database “particularly given its widespread use by other federal, state and local law enforcement agencies in the furtherance of ongoing criminal investigations and fugitive cases.”

Rep. Bennie Thompson (Miss.), ranking Democrat on the House Homeland Security Committee, nonetheless criticized ICE’s extension of contracts for field offices after the “recent problems and resulting public uproar” over the February solicitation.

“While I realize that there may be a legitimate law enforcement need for certain personal information,” he said, “DHS must make sure that contracts of this nature are thoroughly reviewed by its privacy office and Office for Civil Rights and Civil Liberties to ensure compliance with all relevant laws and regulations.”

Commercial license-plate tracking systems are becoming an attractive tool for law enforcement agencies seeking fugitives, drug dealers and other criminals who might be apprehended after their vehicle tags are photographed and logged in the database.

The database that ICE is using for its Houston and Newark field offices is run by California-based Vigilant Solutions. According to the firm, about 3,200 local, state and federal law enforcement agencies use its National Vehicle Locator Service, which grows by 2.7 million records each day.

“As a tool, it was very useful,” said an agency official who has worked criminal investigations in the Dallas field office and was not authorized to comment publicly. “We were after illegal aliens who were wanted on aggravated felonies or who had warrants as drug dealers. It helped narrow down to an apartment complex or city block. You locate the vehicle, then you can start watching the vehicle to find the person. It was very successful.”

But ICE’s use of the database has also raised concerns inside the agency, according to interviews and e-mail correspondence obtained by the Electronic Privacy Information Center, a privacy advocacy group, under the Freedom of Information Act.

“From what I can tell, this data is collected privately and used by law enforcement without the public’s knowledge,” ICE privacy officer Lyn Rahilly wrote in a January 2011 e-mail to an official in ICE’s Homeland Security Investigations division. “There is no accountability to the public as to how the data is collected, how much is collected, how long it is retained, how it is used or what rights affected users might have.”

Said Rahilly: “I certainly understand why law enforcement would want to use this dataset. . . . But the public policy, privacy and civil liberties issues associated with its use are not insignificant.”

Ginger McCall, director of EPIC’s Open Government Project, said the problems identified by Rahilly remain profound. “Until the agency has issued a proper privacy impact assessment and put guidelines into place that will protect privacy, they should suspend the program,” she said. She expressed concern that the data can be used to track a person’s doctor visits or political activity.

Since its founding in 2009, Vigilant has amassed the largest commercial trove of license-plate data in the country, which is offered exclusively to law enforcement agencies across the country.

Company officials said they also accept images from law enforcement agencies, who may also have free access to the database. They offer a “hot-list” service, alerting an agency when any of up to 1,000 license-plate numbers is encountered.

Chris Metaxas, chief executive of DRN, a sister company to Vigilant Solutions, in an interview this year said the National Vehicle Location Service has helped solve “thousands of major crimes” over the years.

“When you’re driving down the block with a camera mounted on cars, it’s simply taking photographs at a high speed — of a piece of metal with numbers on it,” Metaxas said. “A license plate has no expectation of privacy. It’s kind of like taking a picture of a tree.”

According to the e-mails obtained by EPIC, publicly available contract information and officials, at least 10 ICE field offices — about a fifth of all the agency’s law enforcement field offices — have had access to Vigilant’s database since 2011.

Besides Houston and Newark, ICE offices in Dallas, Seattle, Los Angeles, Vermont, San Antonio, Chicago, New Orleans and Washington — which has suboffices in Richmond and Lorton, Va., have used the system.

ICE is not the only federal agency that uses Vigilant’s system. Officers at the Drug Enforcement Administration, the Internal Revenue Service, the U.S. Marshals Service and the FBI have had contracts with Vigilant, according to public contract information.