The Terrorist Watchlist

The Terrorist Screening Dataset (TSDS), more commonly referred to as the Terrorist Watchlist (or the Watchlist) and formerly known as the Terrorist Screening Database, is the U.S. government's consolidated dataset containing sensitive, but not classified, law enforcement and national security information regarding those who are known to be or are reasonably suspected of being involved in terrorist activities (both domestic and foreign).

The Terrorist Screening Center

Administered by the Federal Bureau of Investigation (FBI), and in coordination with the Departments of Homeland Security (DHS), State (DOS), and Justice, and the Office of the Director of National Intelligence (ODNI), the Terrorist Screening Center (TSC) is a multiagency organization, created by a presidential directive in 2003, that manages the Watchlist. Through the Watchlist, TSC provides timely access to identity information regarding known or suspected terrorists (KSTs) for screening partners, including federal, state, and local law enforcement agencies; select international partners; and certain private entities (both domestic and foreign). TSC serves as a bridge between homeland security, law enforcement, the intelligence community, and select international partners for the purpose of sharing terrorism-related information.

ODNI and the National Counterterrorism Center

Nominations of KSTs with a nexus to international terrorism are sent to the National Counterterrorism Center (NCTC; part of ODNI) for inclusion in their database, the Terrorist Identities Datamart Environment (TIDE). If eligible, nominations are passed from NCTC to TSC for potential inclusion in the TSDS. TIDE is the U.S. government's central repository of information (both classified and unclassified) on international terrorist identities. As of October 2020, TIDE contained about 2.5 million identities. U.S. persons (both citizens and lawful permanent residents) account for less than 1% of the total. TSC does not publish the number of Watchlist identities, although media reports indicate that approximately 2 million KSTs were on the Watchlist at the end of CY2023.

Watchlisting Regimen

The federal watchlisting regimen can be divided into three broad processes:

Watchlisting: Involves the submission of information on individuals who may qualify for inclusion as KSTs based on collected intelligence or law enforcement investigations. In their daily work reviewing raw information or case files, staff at U.S. government agencies—dubbed nominators in the watchlisting process—identify people suspected of involvement in terrorist activity. These identities can be nominated for inclusion in the TSDS and/or TIDE.

Verification and Information Sharing: Involves managing records in the TSDS, as well as compiling and exporting special TSDS subsets for various intelligence or law enforcement end users. All nominations for inclusion in the Watchlist are vetted by analysts at either NCTC or FBI and then undergo review at TSC to confirm that they meet the minimum identifying and derogatory criteria for inclusion. TSC regularly reviews data in the TSDS for quality control.

Encounter Management and Identity Resolution: Involves end users checking individuals or identities they encounter against information from the TSDS. Screening and vetting processes can also yield more information on particular subjects that may be fed back into the Watchlist. The following agencies access the TSDS (or subsets of the TSDS) to support their missions:

• Transportation Security Administration – No Fly, Selectee, and Expanded Selectee lists for airline passenger screening (nominations to these subsets of the TSDS must satisfy additional criteria);
• U.S. Citizenship and Immigration Services – Fraud Detection and National Security-Data System for immigration benefits screening;
• U.S. Customs and Border Protection – TECS (not an acronym) system for border and port of entry screening;
• U.S. Immigration and Customs Enforcement – for investigations related to the removal of noncitizens;
• Department of State – Consular Lookout and Support System for visa adjudication and passport issuance;
• FBI's National Crime Information Center – Terrorist Screening Center File to support local, state, tribal, and federal criminal justice agencies for day-to-day operations;
• Department of Defense (DOD) – for military base screening and access.

In addition, Watchlist information is shared with select foreign governments and certain domestic and foreign private entities for screening purposes and to assist in coordination of terrorist threat awareness, assessment, or response.

Civil Liberties and Privacy Protection

TSC is responsible for civil liberties and privacy protection related to the TSDS. Through DHS, individuals can submit a redress inquiry and seek resolution of a complaint related to denied or delayed airline boarding, repeated additional screening, or issues with entry into the United States. For discussion of legal issues surrounding the watchlisting process, see CRS Legal Sidebar LSB11009, Legal Challenges to the Terrorist Screening Database.

Figure 1. U.S. Counterterrorism Watchlisting Regimen

Source: Based on CRS analysis of FBI, TSC, "Overview of the U.S. Government's Terrorist Watchlisting Process and Procedures," as of April 2024; National Counterterrorism Center, "Terrorist Identities Datamart Environment (TIDE)," October 2020; correspondence between CRS and TSC on September 16, 2020; and Christopher M. Piehota, Director, Terrorist Screening Center, Federal Bureau of Investigation, statement before the House Homeland Security Committee, Subcommittee on Transportation Security, Hearing: "Safeguarding Privacy and Civil Liberties While Keeping Our Skies Safe," September 18, 2014. Notes: This figure depicts the process of and the agencies involved in watchlisting. a. The term nomination refers to any proposed change to a TSDS record, including, without limitation, additions of identities, deletions of identities, downgrades of identities, or adding supplemental information to an existing record. b. In addition to its use for screening processes, law enforcement agencies use Watchlist information to support investigations.