Daniel Levitas has written widely about racist, anti-Semitic and neo-Nazi groups and has testified as an expert witness in American and Canadian courts since 1986. His expertise includes such areas as racist violence and the Ku Klux Klan, anti-Semitism, Holocaust denial, the Skinhead movement, Aryan prison gangs, crossburning, and the rural Posse Comitatus. He also has worked throughout the United States with civil rights, religious and community groups, and law enforcement agencies seeking to respond to bias crimes and hate group activity.