SAN FRANCISCO (Reuters) - Federal appeals court judges asked prosecutors on Tuesday why a lower court could seal a ruling that absolved Facebook from having to wiretap a criminal suspect using one of the company’s encrypted services.

FILE PHOTO: A 3D-printed Facebook logo is seen placed on a keyboard in this illustration taken March 25, 2020. REUTERS/Dado Ruvic/Illustration

All three members of the 9th U.S. Circuit Court of Appeals reviewing the matter had tough questions for the U.S. Justice Department’s support for secrecy in a rare higher-court examination of the government’s power to compel technical assistance.

The hour-long oral arguments came in an attempt by the American Civil Liberties Union to force into view at least the legal reasoning from the lower judge who declined to hold Facebook in contempt of court.

Although almost all of that case has been hidden from view, Reuters reported in 2018 that it turned on whether the Wiretap Act, which requires phone companies to help police listen to calls, could also be used to make Facebook break the end-to-end encryption that protects voice calls placed over Facebook Messenger. [here]

In the current case, a judge in the Eastern District of California accepted prosecutors’ contention that the public did not have a right to know why Facebook prevailed on the contempt motion because it grew out of a wiretap request. Applications for those are typically sealed.

The judge also found that even though the suspects had been charged, releasing the ruling could hurt future investigations by revealing government capabilities.

Meeting by video-conference, the appeals judges asked Justice official Scott Meisler in Washington why the public should not be able to see the order, especially if technical aspects were redacted.

“To the extent legal analysis does not implicate the details of the government investigation… I have some trouble understanding why that shouldn’t be made public,” appeals Judge Margaret McKeown told Meisler.

Judge Jacqueline Nguyen said she agreed that the public interest was ”fairly substantial.”

Internet companies are treated differently than phone companies under the law, though Justice Department leaders and some members of Congress have been pushing for new laws restricting strong encryption.

Other fights have been occurring in closed courts and occasionally in the open, as when the FBI failed in 2016 to force Apple to break into an iPhone used by a slain San Bernardino, California, terrorist. Despite the pressure, Facebook has been moving to encrypt more of its offerings.

ACLU attorney Jennifer Granick told the appellate judges that they would be the first in the country to approve sealing an opinion in a criminal matter and that they would be hurting the public’s ability to see how the law of great interest is being applied.

“The sealed opinion may purport to define how far the government can push third parties to facilitate government surveillance of networks the public understands and relies on to be secure,” the ACLU wrote in a brief with the Electronic Frontier Foundation and Stanford cryptography policy expert Riana Pfefferkorn.

“Other technology companies have a right to know the law in this area, to inform their own practices in responding to law enforcement requests,” it added.

While maintaining that the lower judge’s reasoning was inextricably interwoven with sensitive facts, the Justice Department’s Meisler repeatedly asked that if the appellate panel disagreed, it should at least order redactions.