Who is Janis Langwiser from Chasing the Dime: A Novel and what is their importance?

Janis is a criminal defense lawyer, recommended to Henry by Kaz. She works for the small but prestigious firm of Smith, Levin, Colvin & Enriquez with a client list that is so A-list that it isn't listed in the phone book. Langwiser had been employed by the district attorney's office previously and had a career with them that included prosecuting some of LA's higher profile cases. Her manner is confident and professional and after listening to everything Henry tells her, she tells him Renner is bluffing. She calls him to put him on notice that she is Henry's lawyer now.