SAN FRANCISCO — Federal prosecutors have a squeaky clean explanation for how the government acquired logs of some 750,000 calls in a criminal investigation. But defense lawyers are still suspicious that shadowy surveillance programs were used.

Joined by the American Civil Liberties Union and the Electronic Frontier Foundation, defense lawyers in a Northern District drug trafficking case urged U.S. Magistrate Judge Elizabeth Laporte on Monday to compel the government to hand over evidence showing how they screened the defendants’ calls. In an amicus brief filed in October, the groups raised the possibility that the Hemisphere Project—a recently exposed surveillance program in which the government pays AT&T for access to a huge database of calls—had been used to gather evidence against the defendants.

Assistant U.S. Attorney S. Waqar Hasib told Laporte the government gathered the phone data using routine “pen trap orders” and administrative subpoenas.

San Francisco solo Tim Finnegan, a Wiretap Act specialist who argued for the defense, suggested defense lawyers be permitted to review the administrative subpoenas and the data gleaned from them. The defense hopes to file a so-called Franks motion challenging the validity of the subpoenas, but it cannot do so without more information, Finnegan said.

Laporte seemed skeptical that defense lawyers had raised sufficient concerns about the government’s methods to launch such an inquiry.

“You’re supposed to raise some kind of a showing that something was wrong here,” Laporte said. “I don’t have anything.”

Laporte did not rule on the motion to compel discovery but suggested that she would review a handful of the administrative subpoenas in chambers.

The discovery spat has emerged in the prosecution of a drug trafficking ring that spanned California and the Pacific Northwest. Representing Fortunato Rodelo Lara, Jeffry Glenn of Berman, Glenn & Haight in October filed the motion to compel discovery, which was joined by two of the remaining codefendants in U.S. v. Diaz-Rivera, 12-0030.

In its investigation, the government acquired logs from 643 unique phone numbers. One hallmark of the Hemisphere Project, first reported in September by The New York Times, is the ability of government agents to quickly identify a target’s new cellphone number after an old phone is discarded.

The government’s explanation has not dispelled suspicions that the Hemisphere Project or another shadowy surveillance program was used, Hanni Fakhoury, a staff attorney at EFF, said in an interview. He suggested that evidence gleaned from the Hemisphere Project could have been used to obtain administrative subpoenas.

“Before we get to constitutionality of the program, we have to get to the bottom of how the records were created and obtained and see if the defense’s speculation is an accurate assessment of what happened,” he said.

Finnegan raised the possibility that the “source of information” cited in the subpoena might not be an informant, as typically presumed, but a database. Laporte was disturbed by the possibility.

“The court has some inherent authority to police the truthfulness and the transparency of the applications that are made,” she said. “Whenever I’ve seen ‘SOI,’ I’ve always assumed that was a person. I would not want to find out it was a machine.”

Hasib said as far as he knew, all of the sources of information had indeed been human.

“I don’t know where this allegation is coming from other than articles in the press,” he said.

Contact the reporter at jlove@alm.com.