Publication Year


ISBN: 9781552214121-03

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Expert Evidence

Judge as Gatekeeper

From: Lawyer's Guide to the Forensic Sciences


Explores expert evidence, and specifically the judge’s role as the "gatekeeper" who will decide what opinion evidence will be permitted and what will not. The chapter explains how this role has evolved over the past two centuries, and also touches upon the roles of novel scientific evidence, counsel and judges.



Richard D. Schneider

The Honourable Mr. Justice Richard D. Schneider, BSc, MA, PhD, LLB, LLM, CPsych, of the Ontario Court of Justice (appointed 2000), is chair of the Ontario Review Board and deputy judge of the Territorial Court of the Yukon. He was named honourary president of the Canadian Psychological Association in 2002. He was previously a criminal defence lawyer and certified clinical psychologist, working as counsel to the Ontario Review Board from 1994 to 2000. His private practice was generally limited to the representation of mentally disordered accused. Justice Schneider is certified by the Law Society of Upper Canada as a specialist in criminal litigation. He is also an adjunct professor for the Department of Psychiatry, Faculty of Medicine, and Faculty of Law at the University of Toronto. He has also been appointed as alternate chairman of the Nunavut Review Board. A great deal of his time has been spent presiding at the Mental Health Court in Toronto ( Justice Schneider’s major research interests are competency and criminal responsibility. He has published extensively in the area of mental disorder and the law. Recent books include: Mental Disorder and the Law: A primer for legal and mental health professionals (2006, with H. Bloom); Mental Health Courts: Decriminalizing the Mentally Ill (2007, with H. Bloom and M. Heerema); Annotated Mental Health Statutes (2007); The Lunatic and the Lords (2009); Law and Mental Disorder: A Comprehensive and Practical Approach (2013, with H. Bloom) (all published by Irwin Law