There is no shortage of expertise in the USA.

For over 90 years, the Anti-Defamation League (click here) has fought against bigotry and anti-Semitism by exposing and reporting on hate groups and other extremists who seek to harm perceived enemies and to undermine our democracy.  Today, ADL’s Center on Extremism continues our mission to expose and document the groups and individuals whose ideologies and activities perpetuate hatred and extremism.  To this end, the Center on Extremism has created an online resource, Extremism in America, which serves as a guide to prominent extreme movements, groups, and leaders in the United States....