How 'the Terrorist Watch List' Works

— -- For years, the government’s closely held terrorist watch lists have been shrouded in secrecy. But thanks to leaked 2013 government documents first obtained by The Intercept, details of the watch list program have emerged.

Counterterrorism experts interviewed by ABC News believe the documents are authentic.

What Are Terrorist Watch Lists?

What is commonly referred to as "the watch list" is actually a collection of lists, beginning with the Terrorist Identities Datamart Environment (TIDE) run by the U.S. National Counterterrorism Center.

As of July 2013, the TIDE list contained more than 1 million names, according to leaked government documents first obtained by the Intercept. About 280,000 of the names have “no recognized terrorist group affiliation,” according to the documents first released by The Intercept in 2014.

Once a name goes into TIDE, it becomes part of a consolidated terrorist watch list run by the FBI’s Terrorist Screening Center. Subsequent lists run by the various government agencies also draw from the TIDE list.

How Can You Get on the Lists?

The process for placing an individual on watch lists begins with “originators,” who range from everyday citizens to federal agents. Social media posts can also trigger a process for placing individuals on the list. Once an originator passes along a name to law enforcement, counterterrorism officials rely on an elastic set of guidelines in order to add an individual.

Agencies must have “reasonable suspicion” or “articulable evidence” that the person is a “known or suspected terrorist,” according to a document detailing watch listing guidance compiled by the National Counterterrorism Center in March of 2013 and first obtained by the Intercept. The document admits that “irrefutable evidence and concrete facts are not necessary.”

Information about immediate family members and known associates of “known or suspected terrorists” can also be added to the watch list without any suspicion that they themselves are engaged in terrorism.

What Happens When You’re on Watch Lists?

Once your name goes on a list, your information can be shared with the CIA, FBI, the U.S. Department of Defense, state-local-tribal police, U.S. Immigration and Customs Enforcement, U.S. Citizenship and Immigration Services, U.S. Department of State, U.S. Agency for International Development and foreign partners, according to the documents.

From there, your name can be placed into individual watch lists such as the U.S. Transportation Security Administration’s “No Fly” and “Selectee” lists. The No Fly List, which began with just 16 names after 9/11 and has since grown to contain at least 47,000 names, contains individuals prohibited from boarding a plane, while the Selectee List triggers enhanced screening at airports.

Neither list prohibits individuals from purchasing guns.

How Can You Get Off the Lists?

Individuals who believe they have been wrongfully added to a watch list can file a complaint through a redress program, which launches an internal review not subject to oversight by any court or entity outside the counterterrorism community, according to the documents.

The review can result in a removal of an individual’s name, but the individual won’t necessarily be notified because the government maintains a general policy to “neither confirm nor deny an individual’s watch list status,” according to the documents.

Individuals can even be kept on the list after being acquitted of a terrorism charge if authorities still have “reasonable suspicion.”

Not even death can prevent an individual from being added to the watch list because the names of people who have already died can remain or even be placed on the list if authorities believe terrorists may use the deceased’s identity.

The National Counter Terrorism Center did not immediately respond to a request for comment but has said the watch list program is “a critical layer in our counter terrorism defenses.”