"The emphasis of counterterrorism policy in the United States since Al Qaeda's attacks of September 11, 2001 (9/11) has been on jihadist terrorism. However, in the last decade, domestic terrorists--people who commit crimes within the homeland and draw inspiration from U.S.-based extremist ideologies and movements--have killed American citizens and damaged property across the country. Not all of these criminals have been prosecuted under terrorism statutes. This latter point is not meant to imply that domestic terrorists should be taken any less seriously than other terrorists. The Department of Justice (DOJ) and the Federal Bureau of Investigation (FBI) do not officially list domestic terrorist organizations, but they have openly delineated domestic terrorist 'threats.' These include individuals who commit crimes in the name of ideologies supporting animal rights, environmental rights, anarchism, white supremacy, anti-government ideals, black separatism, and anti-abortion beliefs. The boundary between constitutionally protected legitimate protest and domestic terrorist activity has received public attention. This boundary is especially highlighted by a number of criminal cases involving supporters of animal rights--one area in which specific legislation related to domestic terrorism has been crafted. The Animal Enterprise Terrorism Act (P.L. 109-374) expands the federal government's legal authority to combat animal rights extremists who engage in criminal activity. Signed into law in November 2006, it amended the 1992 Animal Enterprise Protection Act (P.L. 102-346). […] This report provides background regarding domestic terrorists--detailing what constitutes the domestic terrorism threat as suggested by publicly available U.S. government sources. It illustrates some of the key factors involved in assessing this threat and concludes by examining potential issues for Congress."
CRS Report for Congress, R42536