Senator Ron Wyden (D-Ore.) and Representative Jason Chaffetz (R-Utah) sent a letter yesterday to Attorney General Eric Holder asking him to release the two Department of Justice legal memos providing guidance to federal prosecutors and investigators about the proper use of GPS devices and other location-tracking technologies. Emphasizing that "there is no room in American democracy for secret interpretation of public law," Sen. Wyden and Rep. Chaffetz told Holder that it is "critical" for both members of Congress and the American public to "understand DOJ's precise views on the current state of the law and existing legal requirements and protections." They requested that the he provide them with unredacted copies of the Justice Department memos by the end of January. (You can read the letter for yourself here .)

The ACLU has also been fighting in court to force release of these memos. The government has technically released them in response to a Freedom of Information Act lawsuit we filed, but they were almost entirely censored. (You can view the heavily redacted documents here and here .) When we challenged the redactions in federal court, the district court judge on the case ordered the government to let him review the memos so that he could determine whether the public has a right to see them, and we are still awaiting the court's decision.

The memos were written in the wake of the Supreme Court's landmark United States v. Jones decision, which held that the government's attachment and use of a GPS tracking device to monitor a car's movements is a "search" within the meaning of the Fourth Amendment. Although Jones struck a major blow for privacy rights, it left many questions about the proper use of surveillance technologies unanswered. The court did not decide whether the government needs a warrant to use GPS devices, and it did not explain how the Fourth Amendment applies to other location-tracking technologies, like cell-phone tracking, license plate readers, and domestic surveillance drones.

While courts sort through these difficult constitutional issues, the political branches are establishing policies to determine when and how government agents may use frighteningly effective new surveillance technologies to track Americans' movements over weeks and months. Because our movements can reveal a ton of information about us—where we go to church, whom we date, whether we see a therapist—these policies will determine how deeply government agents may peer into our personal and professional lives. (To get a sense of how much a government agency, like the DOJ or the NSA, could learn about you through location data, click here .)

As Sen. Wyden and Rep. Chaffetz wrote in their letter, the American people deserve to know what the Justice Department thinks about its Fourth Amendment obligations and what limits it has established to regulate law enforcement's use of the powerful surveillance technologies in its arsenal. Only then can we have a meaningful public debate about whether the government has struck the right balance between effective law enforcement and respect for Americans' privacy. That is why the ACLU continues to demand that the Justice Department release these documents to the public, without all the redactions.