Issues of mental health come into play in many ways in the legal system. Please see my libguide, Medical and Health Data Privacy: HIPAA and Beyond, for information about the privacy of mental health records.
Diagnostic and Statistical Manual of Mental Disorders, by 
Family Guide to Mental Illness and the Law: A Practical Handbook by 
Mental Disability Law : Civil and Criminal by 
Mental Health Law in a Nutshell by 
Representing People with Mental Disabilities: A Practical Guide for Criminal Defense Lawyers by 