Before it started inflicting full-body pat downs on passengers who declined to pass through full body scanners at some domestic airports, the Transportation Security Administration decided to allow some terrorists to board airplanes unscreened because, among other things, it did not want to inconvenience travelers.
It also did not want to tip off some terrorists who were not deemed a threat to the airplane and who were under surveillance.
When Congress funded the Homeland Security Department for fiscal 2009, it required TSA to certify to the House and Senate appropriations committees whether it was going to use the government's full non-classified terrorist watch list -- the Terrorist Screening Database (TSDB) -- to screen passengers boarding airplanes.
The law said that if the TSA determined it "does not need to check airline passenger names against the full terrorist watch list, then the Assistant Secretary shall certify to the Committees on Appropriations of the Senate and the House of Representatives that no significant security risks are raised by screening airline passenger names only against a subset of the full terrorist watch list."
What is the full terrorist watch list, and where does it come from? As set out by a presidential directive issued in 2003, the TSDB includes "individuals known or reasonably suspected to be or have been engaged in conduct constituting, in preparation for, in aid of, or related to terrorism."
The TSDB sits in the middle of an inverted pyramid of government lists of known and suspected terrorists. At the broad top of this inverted pyramid is the Terrorist Identities Datamart Environment (TIDE), maintained by the National Counterterrorism Center, under the director of national intelligence. TIDE includes the identities and derogatory information about every foreign national reasonably suspected of being a terrorist, plus identities of their family members.
The TSDB is one step down from TIDE. It is maintained by the Terrorist Screening Center, a division of the FBI. The TSDB includes the names of people from TIDE who are "known or reasonably suspected of being terrorists" who can be positively identified at places such as airport counters. It also includes the names of a few U.S. citizens, nominated by the FBI.
The Selectee and No Fly lists are subsets of the TSDB. The Selectee list includes "known or suspected" terrorists TSC believes should be set apart by the TSA for enhanced security screening when boarding airplanes, and the No Fly list includes "known or suspected" terrorists TSC believes should not be allowed to board a plane, period.
A report published by the Inspector General of the Department of Homeland Security in July 2009 said that "the No Fly and Selectee lists are intended to prevent specific categories of terrorists from boarding commercial aircraft or subject these terrorists to secondary screening prior to boarding, and are not for use as law enforcement or intelligence-gathering tools."
Following up in the 2009 DHS appropriation, TSA decided only to use the Selectee and No Fly lists -- not the full TSDB -- to screen passengers boarding planes. On Dec. 9, 2008, then-TSA Administrator Kip Hawley sent the mandated certification to the appropriations committees.
"No Fly and Selectee nominations to the TSDB are specifically made by the intelligence community to support aviation and national security," Hawley told the committee. "Another factor is that the TSDB includes records of persons who have been determined to not pose a threat to aviation or national security and are actively being monitored by law enforcement; overt scrutiny prior to boarding an aircraft could jeopardize the related terrorism investigation and would have a negative impact on overall security."
Besides, screening every "known or suspected" terrorist on the full watch list would inconvenience travelers, the TSA believed. "This practice would overburden the Secure Flight system and inconvenience a great number of travelers who are not the individuals identified in the TSDB," said Hawley.
Then, last Christmas, Umar Farouk Abdulmutallab boarded a Detroit-bound flight from Europe, wearing explosive underpants. He was on the TIDE list, but not the TSDB -- and thus not the Selectee or No Fly lists.
President Obama ordered national security agencies to re-examine the watch-listing standards. This summer, they made changes to the system. One of these, according to a counterintelligence official, is that they will now watch-list a person when they get terrorism-related derogatory information about that person from only a single source if they judge that the source is credible.
In Abdulmutallab's case, the single source who provided the lamentably ignored derogatory information happened to be his father.
Testifying before the House Judiciary Committee in March, TSC Director Timothy Healy also said that the government had reviewed the visa status of all known or suspected terrorists and discovered that there "were approximately 1,100 individuals that had received visas that were in the Terrorist Screening Center database."
"I believe most of those have been revoked. They are under review right now," Healy told the committee.
Still, as Americans pass through full-body scanners and pat downs this Christmas season, the inverted pyramid is still in place. Not all "known or suspected" terrorist are on the Selectee or No Fly lists, although those lists have grown.
Earlier this year, there were about 400,000 names on the full TSDB, 14,000 on the Selectee list and 4,000 on the No Fly list. Today, according to a counterterrorism official, there are about 420,000 on the full TSDB, about 18,000 on the Selectee list and less than 10,000 on the No Fly. Less than 5 percent of the people on the No Fly list are Americans.