In NY Times op-ed, Bobbitt suggested FISA to blame for failure to identify 9-11 hijackers; 9-11 Commission report concluded otherwise

In a January 30 New York Times op-ed defending the Bush administration's domestic surveillance program, former National Security Council senior director Philip Bobbitt appeared to contradict the 9-11 Commission by suggesting that regulations under the Foreign Intelligence Surveillance Act (FISA) prevented the U.S. from identifying the hijackers who later committed the September 11, 2001, terrorist attacks. Bobbitt suggested that FISA prevented U.S. officials from tracking "credit card accounts, frequent-flyer programs and a cellphone number" from two of the future hijackers that, in turn, would have likely led to the other 17 men who eventually committed the attacks. But according to the 9-11 Commission report, it was intelligence officials' confusion over the rules concerning intelligence sharing, not FISA's requirements for obtaining warrants to conduct electronic surveillance, that prevented an "investigation of their [the hijackers'] travel and financial activities."

According to Bobbitt, FISA's requirement that investigators show "probable cause" to obtain a warrant for surveillance against "U.S. persons" prohibited investigators from "cross-referenc[ing] credit card accounts, frequent-flyer programs and a cellphone number shared by" the two would-be hijackers the U.S. was tracking at the time, Nawaf al-Hazmi and Khalid al-Mihdhar. Bobbitt then suggested that information would have allowed for "data mining [that] might easily have picked up on the 17 other men linked to" Hazmi and Mihdhar.

From Bobbitt's op-ed:

Consider that on Sept. 10, 2001, the N.S.A. intercepted two messages: "The match begins tomorrow" and "Tomorrow is zero hour." These were not picked up through surveillance of suspected individuals but from random monitoring of pay phones in areas of Afghanistan where Al Qaeda was active. Not surprisingly, these messages were not translated or disseminated until Sept. 12th.

Nor was the fact that we knew the identities of two of the terrorists sufficient to thwart the attack the next day. But had we at the time cross-referenced credit card accounts, frequent-flyer programs and a cellphone number shared by those two men, data mining might easily have picked up on the 17 other men linked to them and flying on the same day at the same time on four flights. Such intelligence collection would not have been based on probable cause, and yet the presence of the hijackers in the country would have qualified them as "U.S. persons."

Clearly, "random" information is likely to be useless when it is not linked to surveillance focused on an individual, while that focused intelligence is much less useful when it is not linked to data mining collected in broad surveillance of "U.S. persons."

But the 9-11 Commission report appears to contradict Bobbitt's account, attributing intelligence officials' failure to conduct an "investigation of their [Hazmi and Mihdhar's] travel and financial activities" to "confus[ion] about the rules governing the sharing and use of information gathered in intelligence channels," not to the FISA requirements. The report specifically noted that criminal investigators "could have conducted a search using all available information" related to Mihdhar because the National Security Agency (NSA), which the 9-11 Commission suggests had already obtained much of this information on Hazmi and Mihdhar, "had approved the passage of its information to the criminal agent" in the criminal case involving the October 2000 bombing of the USS Cole. The report suggested that a search of Mihdhar could have been particularly fruitful, because he was identified by name well before Hazmi.

From the 9-11 Commission report:

It is now clear that everyone involved was confused about the rules governing the sharing and use of information gathered in intelligence channels. Because Mihdhar was being sought for his possible connection to or knowledge of the Cole bombing, he could be investigated or tracked under the existing Cole criminal case. No new criminal case was needed for the criminal agent to begin searching for Mihdhar. And as NSA had approved the passage of its information to the criminal agent, he could have conducted a search using all available information. As a result of this confusion, the criminal agents who were knowledgeable about al Qaeda and experienced with criminal investigative techniques, including finding suspects and possible criminal charges, were thus excluded from the search.

[...]

We believe that if more resources had been applied and a significantly different approach taken, Mihdhar and Hazmi might have been found. They had used their true names in the United States. Still, the investigators would have needed luck as well as skill to find them prior to September 11 even if such searches had begun as early as August 23, when the lead was first drafted.

Many FBI witnesses have suggested that even if Mihdhar had been found, there was nothing the agents could have done except follow him onto the planes. We believe this is incorrect. Both Hazmi and Mihdhar could have been held for immigration violations or as material witnesses in the Cole bombing case. Investigation or interrogation of them, and investigation of their travel and financial activities, could have yielded evidence of connections to other participants in the 9/11 plot. The simple fact of their detention could have derailed the plan. In any case, the opportunity did not arise.