• Stephen Biss

Warning: You Need to Retain an Expert

An excerpt from paragraph 47 of R. v. St-Onge Lamoureux ([2012] 3 SCR 187:

"it is now more difficult to rebut the presumptions. The evidence to be adduced is more complex. The accused must retain a technician or an expert to determine whether the instrument malfunctioned or was operated improperly. It is impossible for a layperson to do this."

You need to retain an expert! The author of this blog is NOT a scientific expert.

Lawyers visiting this blog will be familiar with the rules of evidence concerning expert opinion. Should a member of the public visit this blog and infer that its contents can somehow be used in Court as evidence, I offer the following WARNING.

WARNING: This blog is designed for use by defence lawyers in Ontario only. It is NOT approved by the manufacturers, by the Alcohol Test Committee, by the Centre of Forensic Sciences, police services, or any government authority. Should this blog be used by anyone other than a defence lawyer in Ontario you run the risk that the information contained herein may be unacceptable for your purposes. Please note that the public should NOT attempt to use any of the contents of this blog as evidence in Court. The author is not a forensic expert who gives evidence in Court, but rather a defence lawyer who advocates in Court. Only properly qualified experts can give opinion evidence in Court.

The reality is that any defence lawyer or any member of the public, defending himself or herself in Court (which is not recommended), will need to retain an expert witness to give opinion evidence about the science of evidentiary breath testing or lack thereof.


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For more information respecting this database or to report misuse contact: Allbiss Lawdata Ltd., 303-470 Hensall Circle, Mississauga, Ontario, Canada, L5A 3V4, 905-273-3322. The author and the participants make no representation or warranty  whatsoever as to the authenticity and reliability of the information contained herein.  WARNING: All information contained herein is provided  for the purpose of discussion and peer review only and should not be construed as formal legal advice. The authors disclaim any and all liability resulting from reliance upon such information. You are strongly encouraged to seek professional legal advice before relying upon any of the information contained herein. Legal advice should be sought directly from a properly retained lawyer or attorney. 

WARNING: Please do not attempt to use any text, image, or video that you see on this site in Court. These comments, images, and videos are NOT EVIDENCE. The Courts will need to hear evidence from a properly qualified expert. The author is not a scientist. The author is not an expert. These pages exist to promote discussion among defence lawyers.


Intoxilyzer®  is a registered trademark of CMI, Inc. The Intoxilyzer® 5000C is an "approved instrument" in Canada.
Breathalyzer® is a registered trademark of Draeger Safety, Inc., Breathalyzer Division. The owner of the trademark is Robert F. Borkenstein and Draeger Safety, Inc. has leased the exclusive rights of use from him. The Breathalyzer® 900 and Breathalyzer® 900A were "approved instruments" in Canada.
DrugTest® 5000 is also a registered trademark of Draeger Safety, Inc.. DrugTest® 5000 is "approved drug screening equipment" in Canada.
Alcotest® is a registered trademark of Draeger Safety, Inc. The Alcotest® 7410 GLC and 6810 are each an "approved screening device" in Canada.
Datamaster®  is a registered trademark of National Patent Analytical Systems, Inc.  The BAC Datamaster® C  is an "approved instrument" in Canada.