Yesterday’s Washington Post has an interesting story about the increasingly aggressive role some federal magistrate judges are playing in policing criminal investigations involving digital media. In this “Magistrates’ Revolt”, the judges who review and authorize almost all federal search warrants and digital investigation orders are growing more critical of government assertions–and increasingly publishing their opinions so as to educate and inform their colleagues around the country.

Americans’ privacy rights are regularly decided in secret, where a Department of Justice (DOJ) prosecutor appears before a magistrate judge to ask for authorization to search, seize, or otherwise obtain information relevant to an investigation. Until about 10 years ago, these proceedings did not generally generate published opinions. Only if the evidence was used in a criminal prosecution, and if the government gave the defendant proper notice in discovery, and if the defendant decided to challenge the technique, would there be any public discussion about whether the government had proper legal authority for what it did.

Yet, digital investigations were raising new privacy and police power issues that these magistrates had to decide without the benefit of either the adversarial system or informed public debate. Computers store an immense amount of sensitive information, including personal communications, health information, and financial records. In every computer or database search, given the wealth of private information on a single machine, when a law enforcement agent searches that device, any information responsive to the warrant is going to be intermingled with information about other matters. How should courts ensure that those searches are not fishing expeditions for evidence of any and every potential offense committed by the suspect? Does the plain view doctrine allow officers to examine any file they might see once they’ve legally started examining a computer? The proper scope of digital searches is critical, and the appropriate answers are found in a mix of complex technological, statutory, and common law understandings.

Unfortunately, magistrate judges with only a DOJ  lawyer in front of them would often misplace their faith in government assertions of investigatory power and the relative scope of individual privacy rights. That began to change in the mid 2000’s as computer and communications searches became even more prevalent. The earliest days of the “Magistrate’s Revolt” date back to the issue of cell phone location tracking by the government. In August 2005, Magistrate Judge Orenstein in the Eastern District of New York was the first judge to publish a decision on the issue, and publicly denied a government request to use cell phones as tracking devices without probable cause. In doing so, Judge Orenstein revealed that the Justice Department had routinely been using a baseless legal argument to get secret location tracking authorizations from courts, probably for many years. The government had been using provisions of the Stored Communications Act to get real time cell tower data as an end run around the Rule 41 warrant requirement. Today, the majority of magistrate judges writing opinions on the issue have rejected the DOJ view and require a search warrant for real time cell tracking.

Magistrate Judge Smith of the Southern District of Texas followed up on Judge Orenstein’s work with cell tracking opinions of his own, as well as an opinion denying the government access the numbers you dial after your call has been connected—for example, the digits you dial to use your bank’s automated service, order a prescription, or vote on American Idol—without a warrant. The Department of Justice told courts that these numbers were just like phone numbers dialed, and thus obtainable under the pen register/trap and trace authorities, rather than like the content of communications, albeit expressed in numbers, and thus requiring either a wiretap order or (if stored) a search warrant.

These court opinions were the first time that the public really began to understand that, although there are federal statutes regulating electronic surveillance by law enforcement, the government— in secret ex parte proceedings before magistrate judges across the country—often reaches beyond the authority given to it by law.

The Post highlights the work of D.C. Magistrate Judge John M. Facciola, a former state and federal prosecutor. In a series of cases, Facciola has demanded investigators focus their searches because investigators will come across “innocuous and irrelevant” messages sent by other people “who could not possibly have anticipated that the government would see what they have posted.” He has also insisted that authorities delete collected data that prove unrelated to a current investigation rather than keep them on file for unspecified future use. And Facciola has taken the unusual step, for a magistrate judge, of issuing a series of formal, written opinions that detail his concerns, even about previously secret government investigations.

While Facciola may be remarkable, he is not alone.

He is part of a small but growing faction, including judges in Texas, Kansas, New York and Pennsylvania, who have penned decisions seeking to check the reach of federal law enforcement power in the digital world. Although some rulings were overturned, they have shaped when and how investigators can seize information detailing the locations, communications and online histories of Americans.

Even the Ninth Circuit Court of Appeals back in 2010 expressed concern about the scope of law enforcement searches in the digital age, and has issued advisory guidelines for judges issuing warrants for computer searches. In the course of the Balco professional sports and steroids investigation, the government obtained multiple warrants for the results of ten players’ drug tests. But investigators seized not only the results for the specific players under scrutiny, but also the entire database of results, with samples from hundreds of other athletes.

Objecting to the overbreadth of the search, the Major League Baseball Players Association successfully filed two motions for the return of evidence relating to these other players, and one motion to quash a subpoena. Lower courts ordered the government to return the information that was not related to the Balco-linked players, but the government appealed. The en banc Ninth Circuit endorsed judicial limits on computer searches in United States v. Comprehensive Drug Testing, suggesting that 1) magistrates should insist that the government waive reliance upon the plain view doctrine in digital evidence cases; (2) specialized personnel or an independent third party must segregate and redact the data; (3) warrants and subpoenas must disclose the actual risks of destruction of evidence; (4) the government must design a search protocol to uncover only the information for which probable cause exists; and (5) the government must destroy or return non-responsive data. Academics have debated the wisdom of ex ante judicial limitations on digital searches.

What the Post story reveals is that this debate is far from academic, that these critical decisions continue to be made every day, in secret, and that an small but increasing number of magistrate judges like Facciola, Smith, and Orenstein are working hard to surface these issues so that they may be debated and resolved with the full benefit of open judicial scrutiny and public debate.