The Department of Justice is refusing to disclose details on the government's use of GPS tracking, despite vehement protests from the American Civil Liberties Union. This week, the ACLU obtained two internal memos outlining the DOJ's philosophy on tracking suspects with GPS, but with the exception of some brief background information, the documents were entirely redacted.

The ACLU sued to obtain the memos under the Freedom of Information Act, in a request filed in July. The DOJ, however, declined to release the documents in full, citing an FOIA exemption that safeguards any information that could be used to aid criminals.

"no clear understanding of when we will be subjected to tracking."

"The Justice Department’s unfortunate decision leaves Americans with no clear understanding of when we will be subjected to tracking — possibly for months at a time — or whether the government will first get a warrant," ACLU attorney Catherine Crump wrote in a blog post. "Privacy law needs to keep up with technology, but how can that happen if the government won’t even tell us what its policies are?"

At issue is a February 2012 Supreme Court decision in United States v. Antoine Jones, whereby the court ruled that attaching a GPS tracker to a car constitutes a search, as defined under the Fourth Amendment. While hailed as a victory for privacy advocates, the decision didn't clearly state whether such practices should require a warrant, leaving law enforcement with potentially wide room to operate.

"The ACLU is continuing to fight."

Thus far, the government's interpretation of this decision has remained a mystery, which is why the memos in question are so crucial to the ACLU's quest for transparency. According to the organization, the documents lay out the Justice Department's obligations under the ruling, as well as guidelines for law enforcement agents to follow. The first addresses whether the ruling should be applied to other forms of transportation, such as boats or planes, while the second discusses whether or not the decision has any impact on other forms of location tracking.

The government may be refusing to cooperate, but the ACLU says it will continue to pursue its cause in court. "The ACLU is continuing to fight for release of the memos, and we will ask the court to order the Justice Department to release them because they are being improperly withheld," Crump wrote. "The purpose [of] FOIA is to make sure the government doesn’t operate under secret law—and right now that’s exactly what these memos are."