In April 2003, we reported that watch lists were maintained by numerous federal agencies and that the agencies did not have a consistent and uniform approach to sharing information on individuals with possible links to terrorism. Our report recommended that the Department of Homeland Security’s Secretary, in collaboration with the heads of the departments and agencies that have and use watch lists, lead an effort to consolidate and standardize the federal government’s watch list structures and policies. Subsequently, pursuant to Homeland Security Presidential Directive 6, dated September 16, 2003, the Terrorist Screening Center was established to consolidate the government’s approach to terrorism screening and provide for the appropriate and lawful use of terrorist information in screening processes. The center began “24/7” operations on December 1, 2003, and, about 3 months later, on March 12, 2004, announced that watch list consolidation was completed with establishment of the terrorist-screening database. This consolidated database is the U.S. government’s master repository for all known and suspected international and domestic terrorist records used for watch-list- related screening. Records for inclusion in the consolidated database are submitted to the Terrorist Screening Center from the following two sources: Identifying information on individuals with possible international terrorism ties is provided through the National Counterterrorism Center, which is managed by the Office of the Director of National Intelligence. Identifying information on individuals with ties to purely domestic terrorism, such as Ted Kaczynski (the “Unabomber”), is provided by the FBI. In their terrorist-screening processes, the three federal frontline-screening agencies that we reviewed use records exported by the Terrorist Screening Center. That is, the applicable exported records are incorporated, respectively, into the Transportation Security Administration’s No Fly and Selectee lists, U.S. Customs and Border Inspection’s Interagency Border Inspection System, and the State Department’s Consular Lookout and Support System. The following listing discusses the frontline-screening agencies’ use of watch list records more specifically: Transportation Security Administration’s No Fly and Selectee Lists: As needed, the Transportation Security Administration provides updated No Fly and Selectee lists to airlines for use in prescreening passengers. Through the issuance of security directives, the agency requires that airlines use these lists to screen passengers prior to boarding. The agency’s Office of Intelligence (formerly called the Transportation Security Intelligence Service) provides assistance to airlines in determining whether passengers are a match with persons on the lists. U.S. Customs and Border Protection’s Interagency Border Inspection System: U.S. Customs and Border Protection officers use the Interagency Border Inspection System to screen travelers entering the United States at ports of entry, which include land border crossings along the Canadian and Mexican borders, sea ports, and U.S. airports for international flight arrivals. This system includes not only the applicable records exported by the Terrorist Screening Center, but also additional information on people with prior criminal histories, immigration violations, or other activities of concern that U.S. Customs and Border Protection wants to identify and screen at ports of entry. State Department’s Consular Lookout and Support System: This system is the primary sensitive but unclassified database used by consular officers abroad to screen the names of visa applicants to identify terrorists and other aliens who are potentially ineligible for visas based on criminal histories or other reasons specified by federal statute. According to the State Department, all visa-issuing posts have direct access to the system and must use it to check each applicant’s name before issuing a visa. Also, the Terrorist Screening Center makes applicable records in the consolidated database available to support the terrorist-screening activities of other federal agencies—such as U.S. Immigration and Customs Enforcement, which is the largest investigative component of the Department of Homeland Security—as well as state and local law enforcement agencies. For example, the FBI’s National Crime Information Center has a file—the Violent Gang and Terrorist Organization File— which is accessible by federal, state, and local law enforcement officers for screening in conjunction with arrests, detentions, or other criminal justice purposes. A subset of this file consists of the Terrorist Screening Center’s records to be used to screen for possible terrorist links. Figure 1 presents a general overview of the name-matching process typically used by frontline-screening agencies and airlines to screen individuals against applicable records exported by the Terrorist Screening Center, which has an important role in verifying identities. When the computerized name-matching system of a frontline-screening agency or, in the case of air travel, an airline generates a “hit” (a potential name match) against a terrorist database record, the agency or airline is to review each potential name-match. Any obvious mismatches (misidentifications) are to be resolved by the frontline agency or airline. Conversely, clearly positive or exact matches generally are to be referred to the applicable screening agency’s intelligence center and to the Terrorist Screening Center to provide law enforcement an opportunity for a counterterrorism response. Similarly, hits involving inconclusive matches—that is, uncertain and other hard-to-verify potential matches— typically are to be referred to the applicable screening agency’s intelligence center. In turn, if the intelligence center cannot conclusively determine whether a hit is an exact match, the Terrorist Screening Center is to be contacted. Referring inconclusive matches to the Terrorist Screening Center for resolution or confirmation is important because the possible consequences of not identifying a known or suspected terrorist could be worse than the inconveniences associated with misidentifications. In conducting its research, the Terrorist Screening Center has access to classified data systems that may contain additional information not available to the referring agency. Once the Terrorist Screening Center has confirmed the individual as either a positive match or a misidentification, the frontline-screening agency is to be informed. Homeland security-related screening processes entail some level of inconvenience for all travelers. Also, in an operational context, people can be and frequently are screened for reasons not related to the terrorist watch list but rather for reasons related to an agency’s mission. For example, U.S. Customs and Border Protection screens travelers for any conditions that may make them inadmissible to the country, including past violations of immigration, drug, customs, or other laws. The agency also randomly selects certain individuals for more thorough screening. Similarly, prospective airline passengers may be randomly selected for additional screening, and others may be selected if they exhibit unusual behavior. Generally, screening agencies and airlines are not to disclose the reason they select an individual for more thorough screening measures, so persons may mistakenly assume it is because they are on a terrorist watch list. Annually, hundreds of millions of individuals—international travelers, airline passengers, and visa applicants—are screened against relevant portions of the Terrorist Screening Center’s consolidated watch list. The number of persons misidentified during terrorist watch list screening may be substantial in absolute terms but likely represents a small fraction of the total screenings. Nonetheless, misidentifications resulting from terrorist watch list screening can affect the respective individuals in various ways, with perhaps the most common situation involving delays and related inconveniences experienced by travelers. Although the full universe of persons misidentified by terrorist watch list screening may be substantial in absolute terms, the total number likely represents a small fraction of all persons who are screened. During the 26- month period we studied—from December 2003 (when the Terrorist Screening Center began operations) to January 2006—the center received tens of thousands of screening-encounter referrals from frontline- screening agencies and determined that approximately half involved misidentified persons with names the same as or similar to someone whose name was contained on the terrorist watch list. The number of referrals to the Terrorist Screening Center does not constitute the universe of all persons initially misidentified by terrorist watch list screening because the names of many persons initially misidentified are not forwarded to the Terrorist Screening Center. Rather, by comparing birth dates or other data, the frontline- screening agencies (e.g., U.S. Customs and Border Protection) are able to resolve many initial misidentifications without contacting the Terrorist Screening Center. Additionally, for air passengers, the airlines often are able to resolve initial misidentifications without contacting the Transportation Security Administration. The screening agencies and airlines generally do not maintain readily available statistics on these resolutions. Nonetheless, although the full universe of such misidentifications may be substantial in absolute terms, the total number likely represents a small fraction of all persons who are subject to terrorist watch list screening procedures, as in the following examples: U.S. Customs and Border Protection reported that its officers managed a total of 431 million border crossings into the United States at land, air, and sea ports of entry in fiscal year 2005. Domestic airline flights—flights within the United States—carried 658 million passengers during the 12 months ending January 2006, according to Department of Transportation statistics. The State Department reported that it processed about 7.4 million nonimmigrant visa applications in fiscal year 2005. In addition to these international travelers, domestic flight passengers, and visa applicants, any other person can be subject to terrorist watch list screening in conjunction with routine law enforcement activities. For instance, in stopping a motorist for a traffic violation, a state or local law enforcement officer can check the motorist’s name against the National Crime Information Center’s various files, which include terrorist watch list records exported by the Terrorist Screening Center. The National Crime Information Center, according to the FBI, is available to virtually every law enforcement agency nationwide, 24 hours a day, 365 days a year. People who are misidentified to the terrorist watch list can be affected in various ways, most commonly experiencing delays and related inconveniences, including being subjected to more intensive questioning and searches.