Most real information about extremist violence is obtained by community members reporting on people they fear are up to no good. However, when whole communities feel discriminated against, abused, and mistrusted, they are less likely to come forward for fear that their role will be misunderstood or that well-meaning but mistaken tips will hurt the innocent rather than sparking an honest investigation. In the words of the ACLU, this type of policing makes us both less safe and less free.
