What a terrorist watch list is
The terrorist watch list is officially named the Terrorism Screening Database, which is run by the Terrorist Screening Center of the FBI. This database is the central repository of suspected, as well as known domestic and international terrorists of the country.
It consists of the names of alleged international terrorists given by the Terrorist Identities Datamart Environment that the National Counterterrorism Center maintains with regard to the US intelligence community, as well as security agencies with information about terrorists. It contains data on local terrorists that was presented by the FBI.
The database only has the information needed to identify terrorists and it does not contain any classified information on them concerning what they have done, or how they are being tracked. The Terrorist Identities Datamart Environment keeps classified information on foreign terrorists, whereas the FBI maintains that of the domestic terrorists.
How the terrorism screening database is used
Additional lists are produced based on the Terrorism Screening Database to serve different purposes. For instance, the No Fly and Selectee lists prevent certain individuals from boarding a flight or further scrutinize them. To be part of the No Fly or Selectee list, there should be other evidence on a person’s threat to aviation security, and clear identifying data is required beyond the usual reasonable suspicion.
The Known and Appropriately Suspected (KST) file is the other list derived from the Terrorism Screening Database. Clear identifying information is required to be added to the KST file. The National Instant Criminal Background Check System, which checks the purchases of firearms, questions the KST. Being included on the file does not prevent an individual from purchasing a gun, but marks the purchase to be further reviewed. The person is only allowed to buy a firearm if he is not a felon, fugitive from justice, illegal immigrant, mentally ill or banned from purchasing a gun due to other legal reasons.
Standard of proof required to be included on the terrorism screening database
To be included on the Terrorism Screening Database, government officials recommend a person whom, with “reasonable suspicion”, they believe to be engaged or aid in terrorist activities. However, there should also be an adequate level of identifying information to add the individual on the list. Legal battles on ways to be removed from the No Fly list have been going on and continue up to this moment.