Today the ACLU filed a lawsuit under the Freedom of Information Act to force the FBI to release two memos guiding the bureau’s policy on GPS tracking. The memos were written in the wake of the Supreme Court’s January decision in U.S. v. Jones, which held that the Fourth Amendment applies when the government secretly attaches a GPS device to a car and tracks its movements. (See today’s legal complaint, our original FOIA request (made July 18), and a blog post we wrote about that request).

The Jones decision shed some light on the proper use of GPS devices by law enforcement, but it leaves several issues unresolved. For instance, is GPS tracking the sort of search that obligates law enforcement agents to obtain a warrant based on probable cause? Is GPS use proper if an agent has a reasonable belief that a search would turn up evidence of wrongdoing? Does Jones apply to other types of searches, such as tracking the location of a cell phone?

The two memos we’ve asked for may show how the FBI has resolved these unanswered questions. We know about the memos’ existence from a talk given by FBI General Counsel Andrew Weissmann in February. He said that one memo focuses exclusively on the use of GPS tracking, and suggested that it covers questions like whether Jones applies to other forms of transportation like airplanes and boats, and whether it applies at international borders. Weissmann said the other memo sets forth the FBI’s guidance on how Jones applies to other evidence-gathering techniques, beyond GPS.

It is no secret that the FBI is a powerful agency with influence over other law enforcement agencies. At the time of the Jones decision, the FBI had 3,000 GPS devices in use. The bureau says its mission is to perform “responsibilities in a way that is responsive to the needs of the public and faithful to the Constitution of the United States.” In line with that mission, the American public should know how those GPS devices and other evidence gathering technology are being used. The FBI should release the two memos on the Jones decision to allow the American public to know how the agency will handle future investigations.

Catherine Crump, our attorney on this case, had this to add:

Collecting personal data is increasingly easy for the government to do but hard for citizens to detect, so it’s more important than ever for the American public to know the rules that law enforcement is operating under, especially when it comes to location tracking. Knowing the FBI’s position on what it can and can’t do in investigations is essential if America’s privacy laws are going to keep up with technology.

Congress is currently considering a bill supported by the ACLU, called the Geolocation Privacy and Surveillance Act (the GPS Act), that would require law enforcement to get a warrant to access a person’s location information through GPS or cell phone tracking. (You can click here to send a message asking Congress to support the GPS Act.)