Reports show a US intelligence agency has been buying location data from tech companies. 

A legal loophole has allowed the US Defense Intelligence Agency (DIA) to collect location information without a warrant, according to The New York Times.

A memo written to a Senator (PDF) has revealed that the DIA has been buying information from data brokers, who collect it from third-party apps.

In November last year, the US Department of Homeland Security came under investigation after Buzzfeed revealed it had been collecting phone location data without warrants for immigration enforcement.

Around the same time, Vice reported that US Special Operations Command was buying location data from an Islamic prayer app called Muslim Pro.

This all comes despite the fact that a 2018 US Supreme Court decision ruled warrants are necessary for gathering location data. 

The ruling, known as the Carpenter decision, found that the Fourth Amendment requires investigators to go through an official process to access the data. The state had tried to argue that mobile phone users know they are continually handing over their location information to their service providers, so they had already given up that information willingly, and should not have an expectation of privacy as a result.

But the DIA says it is aware of the ruling and is not operating in breach of it. 

“The DIA does not construe the Carpenter decision to require a judicial warrant endorsing purchase or use of commercially-available data for intelligence purposes,” the agency said in its memo. 

The DIA says that it has been buying a mix of US and foreign data, and claims to be putting data from US residents in a separate database that requires special permission to access.

The Carpenter case was argued by the ACLU in the Supreme Court. ACLU Senior Staff Attorney Ashley Gorski says the DIA memo reveals government agencies are finding new ways of ignoring the law.

“The government cannot simply buy our private data in order to bypass bedrock constitutional protections,” Ms Gorski told reporters. 

“Congress must end this lawless practice and require the government to get a warrant for our location data, regardless of its source.”