Earth Liberation Front (ELF) is a grassroots environmental group that the Federal Bureau of Investigation labeled "a serious terrorism threat." Since 1996, ELF and the Animal Liberation Front (ALF) committed more than 600 acts of vandalism that resulted in more than $43 million in damage, an FBI terrorism expert reported to Congress in 2002.

James Jarboe, the FBI section chief for Domestic Terrorism, told Congress that it was hard to track down ELF and AlF members because the two groups have little organized structure. According to the ELF link on the ALF Web site, there is no designated leadership nor formal membership. ELF and ALF claim responsibility for their activities by e-mail, fax, and other communications usually sent to the media.

In 2002, media information was provided by the North American Earth Liberation Front Press Office. Spokesman Leslie James Pickering wrote that he received anonymous communiqués from ELF...