Electronic surveillance by law enforcement is at the center of legal debates across the country. (Issei Kato/Reuters)

A federal judge released a list Wednesday of all sealed requests made in Washington in 2012 for Americans’ telephone and Internet activity, a step toward bringing more public scrutiny to rapidly expanding secret law enforcement activities.

The action came in a case brought by a journalist to unseal a much larger collection of information about court-ordered electronic surveillance in closed criminal investigations in the nation’s capital.

Legal experts say even the selective release appears to mark the first time a U.S. district court has made a systematic online disclosure of how often law enforcement seeks court orders under a 1986 statute to obtain individuals’ electronic records from communication service providers. The release could serve as a model for court disclosure elsewhere, several legal experts said.

U.S. District Chief Judge Beryl A. Howell of the District identified 235 law enforcement applications from 2012 from investigators seeking to collect the time, date, duration and source of communications to and from a targeted person, phone number or email address, or instant messaging or social network identity. The applications for what are known as pen register and trap and trace orders do not allow law enforcement to access the contents of conversations.

In a 53-page filing, Howell identified applications by case number, date filed, reviewing judge and whether the request sought information about a cellular number or email address.

“We are pleased that the courts seem to be recognizing that they have been, perhaps inadvertently, party to creating a culture of secrecy around the government’s use of surveillance tools,” said Cindy Cohn, executive director of the Electronic Frontier Foundation, a reaction shared by several civil liberties groups.

A spokesman for U.S. Attorney Channing D. Phillips, whose office prosecutes federal and local crimes in the District, declined to comment beyond what the office has said in court filings.

In filings, prosecutors wrote that they agreed in principle that surveillance applications and orders did not necessarily need to be permanently sealed. They also proposed making public some details from a small sample of the 235 applications from 2012 in cases that have ended.

Prosecutors said they would unseal information such as what type of crime was being investigated, but not what agency sought the order, specifics about the case, or material that would identify individuals, targeted numbers, accounts or service providers.

“If the procedure here goes well, it may set an important precedent other courts can follow,” said Orin S. Kerr, a George Washington University law professor and former Justice Department lawyer specializing in computer crimes.

The release responded to a sweeping public-records petition by investigative journalist Jason Leopold of Vice News that was joined recently by the Reporters Committee for the Freedom of the Press. Leopold’s 2013 request sought all government electronic surveillance applications and orders in closed investigations that directed private service providers to turn over users’ call information as well as information related to tracked devices, stored emails or customer records.

The request to unseal records comes as courts increasingly take up cases testing the constitutional limits of law enforcement searches in an electronic era.

Civil liberties groups and advocates for government transparency have raised alarms that new surveillance methods coupled with computing and storage capabilities enable authorities to use laws that date to a copper-wire and telephone exchange world to sweep up vast amounts of digital data to map much of a person’s movements and social relationships without a search warrant.

The U.S. Supreme Court in 2014 ruled unanimously that police generally must obtain a warrant to search cellphones. But legal battles continue to work through appellate courts over such questions as whether a warrant is required to collect cellphone information using new technology devices that mimic cell towers. The devices are operated by law enforcement — not communications companies — and can covertly capture a target’s phone location and other information in real time.

A Maryland appeals court in March admonished police and prosecutors for deceiving courts by using the 1986 law to justify secretly deploying the tower-mimicking equipment, which are called cell-site simulators and branded under names including StingRay, Triggerfish and Hailstorm.

Police seeking a surveillance order under the statute must tell a court only how the information they’re after is relevant to an investigation. The legal threshold for getting a search warrant is higher and requires law enforcement to show a judge they have reason to believe that a particular crime has been committed.

The court said using the simulators without first getting a search warrant amounted to “constitutionally intrusive conduct.”

Courts in recent years have also questioned police requests to use the surveillance orders to collect numbers such as passwords that are dialed after a phone call is connected.

Leopold’s request to unseal records is an attempt to find out how often and in what kinds of cases law enforcement asks to track electronic data and to read the facts law enforcement provide to explain why the tracking was warranted.

Information that has emerged underscored how murky the answer is. In a court hearing Friday, prosecutors said that based on a preliminary assessment from the court, applications under the 1986 law quadrupled in the District from 2012 to 2013 alone, climbing from 137 applications to 564. Howell’s order Wednesday said that upon more detailed review, the court found 235 applications in 2012, and it did not address how many were filed the following year.

Nationwide between 2004 and 2013, the use of such orders by Justice Department agencies climbed sevenfold, to more than 42,000, department records show.

Jeffrey Louis Light, the attorney for Leopold, said that while all sides in the case have agreed that surveillance requests should not be kept secret indefinitely, they rarely become public.

Courts do not file or docket them electronically in any uniform way to help track or identify them. In Houston, for example, surveillance requests are maintained separately from regular criminal and civil dockets, filed on paper, “sealed in paper envelopes and tucked away in a vault somewhere . . . so it would difficult to find them even if someone wanted to,” said U.S. Magistrate Judge Stephen W. Smith, a longtime advocate for greater openness.

Likewise, the Alexandria division of the federal court for the Eastern District of Virginia in Alexandria keeps a “running list” of case numbers for the surveillance requests that is only available in person at the clerk’s office or upon written request with payment of copying fees, the office said.

The existence of the running list surfaced in a 2013 appeals court order that arose out of a case in which three individuals challenged a government attempt to get their Twitter records.

Also, some of the only people outside government who know of the orders — the targets of the investigation — often do not have a motivation or the means to unseal the orders.

Assistant U.S. Attorney Pamela S. Satterfield said the government continues to view Leopold’s request as “overbroad” and had not taken a position yet on whether the First Amendment or other law required the unsealing of the court documents he requested.

Still, prosecutors and the court’s first step in the case “is a fantastic and welcome sign of progress toward greater transparency in the courts,” said Nathan Freed Wessler, staff attorney for the American Civil Liberties Union’s speech, privacy and technology project.

Added Kerr: “If the government is willing to cooperate, it’s a positive sign. There’s no downside, and at least some upside.”