1001: Known as the "Al Capone," Title 18, Section 1001 of the federal criminal code covers the crime of lying to federal agents. Just as the government prosecuted Capone for tax violations, it has frequently used 1001 against terrorism defendants whose crimes or affiliations it couldn't prove in court.
Agent provocateur: An informant or undercover operative who incites a target to take unlawful action; the phrase originally described strikebreakers trying to provoke violence.
COINTELPRO: From 1956 to 1971, the FBI's Counter Intelligence Program attempted to infiltrate and sometimes harass domestic political groups, from the Ku Klux Klan to the National Lawyers Guild and the Southern Christian Leadership Conference.
DIOG: The Domestic Investigations and Operations Guide, a 258-page FBI manual for undercover operations and the use of informants. Recently revised to allow agents to look for information—including going through someone's trash—about a person who is not formally being investigated, sometimes to flip them as an informant.
Domain Management: An FBI data-mining and analysis program used to map US communities along ethnic and religious lines.
Hip pocket: An unregistered informant who provides information and tips to FBI agents but whose information is not used in court.
Joint Terrorism Task Force: A partnership among federal and local law enforcement agencies; through it, for example, FBI agents can join forces with immigration agents to put the squeeze on someone to become an informant.
Material support: Providing help to a designated foreign terrorist organization. This can include money, lodging, training, documents, weapons, and personnel—including oneself, and including joining a terrorist cell dreamed up by the FBI.
Operator: Someone who wants to be a terrorist; in the FBI's view, sympathizers become operators.
Predicate: Information clearly suggesting that an individual is involved in unlawful activity; it's required for the FBI to start an investigation.