Accidental Death of an Anarchist Lesson Plan

How does the Maniac claim he cannot be held accountable for the initial charges levied against him in the first scene? How does this help his case?

Bertozzo initially tells the Maniac that he is charged with impersonation. In particular, he is charged with impersonating a psychiatrist and charging a family 200 to fraudulently diagnose their son with schizophrenia and get him committed to a mental institution. The family has brought this to the police's attention, so the Maniac is now being questioned by police. However, this is actually the twelfth charge of impersonation against the Maniac, though he's never been convicted. The Maniac justifies all of these incidents...