Public discussion of the purpose and meaning of roving wiretap authority has focused on targeting individual terrorists or spies who seek to evade detection. But Judge Vinson accepted a Justice Department proposition that the target could be Al Qaeda in general, so if the N.S.A. learned of a new Qaeda suspect, it could immediately collect his communications and get after-the-fact approval.

Leaks by Edward J. Snowden, a former intelligence contractor, brought to light that the FISA court secretly interpreted another provision of the Patriot Act, known as Section 215, to permit the bulk collection of records about Americans’ phone calls in 2006. Public discussion of that provision had focused on F.B.I. requests for business records, akin to how it would use a grand jury subpoena.

Judge Vinson’s acceptance of this after-the-fact approval process was a turnaround. Seven weeks earlier, when he rejected Judge Howard’s interpretation of FISA, Judge Vinson had emphasized the importance of having judges review whether a target met probable cause standards before surveillance started, to protect Americans’ Fourth Amendment rights.

Judge Vinson’s ruling apparently provoked concerns by several of his fellow judges on the surveillance court when the N.S.A. sought retroactive approval for its surveillance of new phone numbers and email accounts. That led to Judge Vinson’s August 2007 ruling clarifying what his order had empowered the N.S.A. to do.

His August opinion noted that other judges — George P. Kazen, John D. Bates, Dee Benson, Frederick J. Scullin Jr. and Colleen Kollar-Kotelly — had raised concerns that the N.S.A. may have known about some of the newly targeted email addresses and phone numbers before Judge Vinson’s order in May. Roving wiretaps are reserved for investigations in which the accounts the targets will be using are “unknown” at the time of the order.

But Judge Vinson insisted that it was acceptable for the N.S.A. to use the power to target accounts it already knew about, too, so long as analysts had not yet completed the process of “connecting the dots” until after the application for the order. He wrote that “it is appropriate to grant the government as much latitude in initiating surveillance as the statute can reasonably be construed to permit.”

Judge Vinson’s program was short-lived. On Aug. 5, 2007 — three days after his second opinion — President George W. Bush signed into law the Protect America Act, which amended FISA to authorize warrantless surveillance targeting foreigners. Judge Vinson’s May 31 order expired on Aug. 24, and the Justice Department did not seek its renewal.