Magistrate Judge John Facciola, right, is seen in a file photo during an event in which students argued court cases as part of a competition. Also seen, from left to right, are Professor Jamin Raskin, Judge Emmet G. Sullivan and Magistrate Judge Deborah A. Robinson. (Rich Lipski/The Washington Post)

Judges at the lowest levels of the federal judiciary are balking at sweeping requests by law enforcement officials for cellphone and other sensitive personal data, declaring the demands overly broad and at odds with basic constitutional rights.

This rising assertiveness by magistrate judges — the worker bees of the federal court system — has produced rulings that elate civil libertarians and frustrate investigators, forcing them to meet or challenge tighter rules for collecting electronic evidence.

Among the most aggressive opinions have come from D.C. Magistrate Judge John M. Facciola, a bow-tied court veteran who in recent months has blocked wide-ranging access to the Facebook page of Navy Yard shooter Aaron Alexis and the iPhone of the Georgetown University student accused of making ricin in his dorm room. In another case, he deemed a law enforcement request for the entire contents of an e-mail account “repugnant” to the U.S. Constitution.

For these and other cases, Facciola has demanded more focused searches and insisted that authorities delete collected data that prove unrelated to a current investigation rather than keep them on file for unspecified future use. He also 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.

“For the sixth time,” Facciola wrote testily, using italics in a ruling this month, “this Court must be clear: if the government seizes data it knows is outside the scope of the warrant, it must either destroy the data or return it. It cannot simply keep it.”

One of the shirts that Judge James Orenstein of Brooklyn designed. (Photo courtesy of Stephen Smith)

The Justice Department declined to comment for this article, although it said in an appeal to a Facciola ruling this week that his position was “unreasonable,” out of step with other judges and would slow searches of the e-mails of criminal suspects “to a snail’s pace.”

Facciola, 68, a former state and federal prosecutor known as “Fatch” around the limestone E. Barrett Prettyman Federal Courthouse a block from the Mall, remains an outlier among the 500-plus federal magistrates nationwide, say legal experts.

Yet 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.

“There’s a newfound liberation to scrutinize more carefully,” said Albert Gidari Jr., a partner at Perkins Coie who represents technology and telecommunications companies. “They also don’t want to be the ones who approve an order that later becomes public and embarrassing. . . . Nobody likes to be characterized as a rubber stamp.”

‘Magistrates’ Revolt’

The seeds of what legal observers have dubbed “the Magistrates’ Revolt” date back several years, but it has gained power amid mounting public anger about government surveillance capabilities revealed by former National Security Agency contractor Edward Snowden. Judges have been especially sensitive to backlash over the Foreign Intelligence Surveillance Court, which made secret rulings key to the growth of the surveillance programs.

Central to the cases before magistrate judges has been the Fourth Amendment’ s prohibition of unreasonable search and seizure. Inspired by the Founding Fathers’ unhappy memories of the aggressive tactics by British soldiers, it has been continually reinterpreted through more than two centuries of technological change.

Such issues are increasingly urgent in an era when a typical smartphone carries video clips, e-mails, documents, location information and enough detail on a user’s communications to allow authorities map out a nearly complete universe of personal relationships. The Supreme Court plans to hear two cases next week on issues related to how police search cellphones after arrests.

Magistrate judges, who do much of the routine work of the criminal justice system, influence each other through conversations at judicial conferences and through the federal e-mail system, which allows any magistrate judge to query all others on a vexing legal question with a single click of the mouse.

Published opinions by magistrates are relatively rare, making it hard to track shifting attitudes toward government data requests. But legal experts say the overall level of skepticism from magistrates is on the rise.

“In talking to magistrate judges, they are saying, ‘I’m not writing anything. I’m just saying no,’ ” said Brian L. Owsley, a former magistrate judge now teaching at Texas Tech’s law school.

Magistrate Judge Stephen W. Smith, based in Houston’s federal court, is often credited with touching off the insurrection among his colleagues with a 2005 ruling in which he denied a government request for real-time access to the detailed location information that cellphones emit. He ruled that requiring a telecommunications company to provide subjects’ ongoing data amounted to placing a tracking device on them — something permitted only with the issuance of a search warrant, which the government had not requested.

The distinction is crucial: Search warrants require that the government show probable cause that a crime was committed and that the search will turn up evidence that helps prove the crime. Other magistrates had routinely allowed cellphone location data to be seized using court orders, which require the government to meet a less stringent standard of showing only that the information is “relevant and material” to an ongoing investigation.

“We understand law enforcement has a difficult job, and we don’t want to blow an investigation or tip off a suspect,” said Smith, who has known Facciola for years through their shared work for an online legal journal. “On the other hand, he feels, like we all do, the special responsibility to safeguard the Fourth Amendment. . . . We are the ultimate backstop.”

Tackling such issues, even in the face of possible reversal by higher courts, has become something of a badge of honor among some magistrates. Judge James Orenstein of Brooklyn, a former federal prosecutor who also wrote an early, influential ruling on cellphone location data, once joked with Smith that they would soon have enough like-minded magistrates to form a bowling team, Smith recalled.

That prompted Orenstein to design shirts featuring the image of a bowling ball rolling toward a cellphone and nine cell towers arranged in a triangle like a set of bowling pins. Above the image it read, “CSI: Cell Site Information.” Below it read, “Bowling for Dialers.”

When other magistrates write opinions on the issue — regardless of which side they take in the debate — they are offered one of the shirts.

20 warrants modified

Facciola, whose chambers are on the floor below where the secretive Foreign Intelligence Surveillance Court meets, has been a magistrate since 1997. Despite a record of challenging law enforcement, legal observers say he has taken a new, more public role in digital privacy cases since he was reappointed for a third term in June. He declined interview requests for this article.

In one recent opinion, Facciola estimated that he has modified about 20 search warrants in the last six months. In rejecting the search of the Georgetown student’s iPhone last month, Facciola warned that with electronic devices, “the potential for abuse has never been greater: it is easy to copy them and store thousands or millions of documents with relative ease.”

He also demanded to know — in precise technical language — how the government intended to search those documents. “The government should not be afraid to use terms like ‘MD5 hash values,’ ‘metadata,’ ‘registry,’ ‘write blocking’ and ‘status marker,’ nor should it shy away from what kinds of third party software are used and how they are used to search for particular types of data,” he wrote.

Facciola ultimately approved the warrant to search the Navy Yard shooter’s Facebook account last fall, but only after limiting the type of information the company could give the government. Law enforcement officials, he wrote, should narrowly craft their requests 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.”

In two other cases, he has raised concerns about government requests to prevent Twitter and Yahoo from notifying customers of grand jury subpoenas involving the users’ information. Facciola also took the unusual step this month of inviting the Electronic Frontier Foundation, a civil liberties group, to serve as a counterpoint to the government’s request for cellphone location information in a robbery investigation. He expressed particular interest in how the technology works, how long the data are stored and how precisely the data can locate a person within an area.

“We’re hearing from an increasing number of magistrates that they’re uncomfortable with the requests they’re getting from the FBI and the Justice Department for surveillance,” said Cindy Cohn, legal director of the Electronic Frontier Foundation.

Facciola has twice in recent rulings denied requests to secretly search e-mails related to the investigation of possible kickbacks involving a defense contractor. First, he objected to the Justice Department’s request for the “entire universe” of information related to a particular account and compared the broad request to rummaging randomly through a person’s belongings.

When an investigator renewed the request a few weeks later, Facciola dismissed it as “the same defective and unconstitutional request” and said he had no choice but to order the a narrower search to be performed by the service provider, Apple, rather than the government. He referred to an earlier opinion by Magistrate Judge David J. Waxse, based in Kansas City, who had suggested a similar approach in a 2012 case, saying that turning over the entire contents of an e-mail account to authorities was equivalent to giving police every piece of mail sent to a home, instead of only those letters demonstrably related to an investigation.

Such rulings have set off alarms across the tech industry, prompting companies to worry that they could be dragged into the machinations of the criminal justice system. Outside legal scholars raised serious concerns as well.

Orin Kerr, a George Washington University law professor and former Justice Department attorney specializing in computer crimes, said several of Facciola’s opinions are “effectively daring the Justice Department to appeal him as a way of starting a conversation.”

Challenge by Justice

The Justice Department obliged Monday. It filed an appeal that called Facciola’s approach to searching e-mail contrary to the rulings of other courts and said that it would be impractical to have employees of a private company, instead of trained government investigators, searching for evidence.

The U.S. attorney for the District of Columbia has appealed at least two of Facciola’s recent decisions in filings that remain under seal. The judge has had mixed results when the Justice Department challenges his decisions.

In the leak investigation involving Fox News reporter James Rosen, for instance, Facciola ruled that the government was obligated to notify the reporter that his Gmail account was the target of a warrant. U.S. District Judge Royce C. Lamberth reversed Facciola. The warrant was served on Google, the service provider, and Lamberth said the government had no obligation to notify Rosen.

Other magistrates who set a high threshold for collecting digital evidence have been overruled on appeal or have seen their rulings modified. Magistrate Judge Lisa Pupo Lenihan, based in Pittsburgh, sided with Smith and Orenstein in requiring a search warrant before cellphone location data was turned over to police. The court’s other magistrate judges signed on as well.

But a federal appeals court overruled Lenihan in a 2010 decision that allowed magistrates to require probable cause only “sparingly,” in cases that clearly merit it. That left the standard — along with many issues involving what digital evidence the government can collect and how — a patchwork across the country that attorneys sometimes struggle to navigate.

“The decisions are getting to be increasingly inconsistent,” said Marc Zwillinger, founder of ZwillGen, a Washington-based law firm that has major tech companies as clients. “It places a provider in a difficult position, accepting an order from a judge in one district that a judge in another district would find unconstitutional.”

Alice Crites and Carol D. Leonnig contributed to this report.