Ask an Impaired Driving Lawyer

What are My Chances?

See also: Can I fight My Criminal Charge?


Can I Fight My DUI Charge?


The Best Approach to Defending a DUI


The public, the Government of Ontario, and the Courts take a dim view of drunk driving. Expect vigorous prosecution by very competent Assistant Crown Attorneys who operate under strict guidelines that preclude plea-bargaining.  

Despite what you may have been told by your buddy, there is virtually no plea bargaining in DUI cases in Ontario. It is also NOT TRUE that you can keep your driver's licence for work purposes if you are convicted of impaired driving laws in Ontario. You will need to have a trial and be found not guilty if you wish to keep your licence.

Canadians are innocent of impaired driving until they are proven guilty beyond a reasonable doubt. You can ask for a trial and you will get one about six to ten months after the alleged offence. You can defend yourself but that is not wise. The defence of an impaired driving charge by an impaired driving lawyer requires the most creative advocacy, technical, and legal skills imaginable. 


The "Show Up" Defence aka "Witness Roulette"

Over my many years as a part-time Assistant Crown Attorney in Peel and elsewhere, I have been amazed at the number of times that an accused got the benefit of typographical errors in the Certificate of Analysis, calibration errors by the qualified technician, or stupid errors by the arresting officer. Sometimes an astute Crown can fix them, sometimes the day of trial is too late. Particularly in cases where Intoxilyzer readings are close to the legal limit, judges may have a reasonable doubt based on some very technical omission by the arresting officer or the breath tech.

You may wish to hire an impaired driving lawyer with instructions to run a trial and see what happens. This is the least expensive kind of trial. If this is the only approach your lawyer tries, about 85% of the time you will lose and be convicted but it may be worth your while simply to set the matter down for trial and see what happens.

This won't work at all unless your lawyer has the experience required to notice and take advantage of such errors.


The "Prove It" Defence 

I know of one legendary Brampton impaired driving lawyer, now deceased, who was a master of this approach in the 1970's and 1980's. He would listen very carefully to everything the police officers said making very few notes. He'd find a very simple error, note it, widen it, and use it to raise a reasonable doubt.

Obviously there are better results proportional to the lawyer's experience as a defence counsel and Crown. A criminal law lawyer familiar with this field knows what to watch for. The case law surrounding impaired driving is extensive.


The "Carter" Approach   

Let's assume that:

  1. when you started dinking you were alcohol free

  2. you remember exactly how many beers you drank

  3. you drank all the same brand

  4. you know exactly what time you started

  5. you have a receipt from the bar

  6. you have witnesses to confirm your evidence

If an  expert toxicologist is given this information, your weight, and drinking experience, then the toxicologist can do a mathematical calculation to determine what your blood alcohol concentration was at the time of driving. It used to be that if the judge believed your evidence and that of your witnesses, and that evidence contradicted the Intoxilyzer results at the time of the Intoxilyzer tests then you raised a reasonable doubt based on "evidence to the contrary." The toxicologist might, however, have to do experiments on your body to find out your exact "elimination rate". The experiments aren't pleasant, I've been though it.

This approach required hiring a both a lawyer and a toxicologist.

There were better results if readings were in the 90 to 109 mg/100mLs range. We would try it if you had good evidence of what you drank and when. Clients should never try to concoct a defence using this approach - because they would get caught.

Unfortunately, on July 2, 2008, Parliament did its best to abolish this defence. The Harper Government enacted a rule that if an approved instrument, e.g. an Intoxilyzer, says you are Over 80 then you are Over 80, whether you are guilty or innocent. You can have 15 witnesses, videotape, and restaurant receipts proving what you drank, but that combined with the opinion of a toxicologist is not enough for an "evidence tending to show defence". Now, as of December 2018, we have even more difficult legislation in Bill C-46, that is designed to eliminate any defence, whatsoever, where the accused believes that the readings are false and tries to contradict them or show that the breath tests were not reliable.   

Most defence lawyers think that this legislation violates section 7, 8, and 11(d) of the Charter but it will take time before this issue gets sorted out in the Supreme Court of Canada. In the interim if you want to try it and you really are innocent you shouldn't be afraid to retain a very experienced lawyer to diligently fight the necessary challenges of disclosure, retrospectivity, and constitutionality.


The Charter of Rights Approach

There are many mistakes that police officers can make respecting reason for the stop, physical tests ASD tests questioning outside the law but prior to right to counsel, ASD reasonable suspicion, ASD identification, ASD demand, ASD timing, R & PG, arrest, Intoxilyzer demand, demand timing, right to counsel, Brydges duty counsel advice, right to interpreter, delays in attendance at detachment, counsel of choice, technician's demand, second request for counsel, delay at the detachment, and delayed release that can result in a Charter of Rights application for exclusion of evidence. Our USA DUI Attorney friends call it suppression of evidence.

The very best impaired driving counsel will use this approach. It requires a very careful analysis of the disclosure, knowledge of case law, and service 30 days advance notice on the Crown. You can't realistically draft the required Charter notice without the assistance of a lawyer.

Sometimes, through no fault of the accused, the case drags on for 14 or 15 months. An astute impaired driving lawyer counsel will have built a record of objections to each delay caused by late Crown disclosure, systemic delay by the Trial Co-ordinator, courtroom overbooking, and Crown precipitated adjournments. It is amazing how many impossible cases are won by defence counsel simply being there in person on every Court appearance to object at every Court attendance to Crown or systemic delay.


The Actively Participating Client Approach

Let's suppose that an officer says that he or she saw you weaving down a one km stretch of road. You hire a surveyor to survey all of the roadway showing its twists and turns. You hire a videographer to video normal drivers under optimal daylight summer conditions doing the normal weaving that happens on every narrow twisting roadway.

Let's suppose that an officer says that he or she followed you south down Erin Mills Parkway starting at Britannia Road and stopping you at Battleford Road in Mississauga. You hire someone to drive the route with a GPS and software that tracks and shows the route is impossible because Battleford is north of Britannia.

Let's suppose that an officer says you were stumbling in a parking lot. You hire a private investigator to inventory every surveillance camera in the plaza and you ask me to get a Court order forcing the stores to hand them over for evidence.

Let's suppose that your car was totalled in an accident and you are charged with care or control.  You do not allow the automobile to be destroyed. Rather you arrange for a professional photographer to take extensive photographs of the vehicle and you hire an accident reconstruction expert to pursue a Wren defence. 

Let's suppose an off-duty officer driving his private vehicle claims that you cut him off on a highway. He pursues pulling alongside your vehicle and frightening your family. You respond by taking evasive manoeuvres. Your actions can be substantiated by your family.  You and a friend take video of the entire route travelled showing the bumps, the twists and turns, and visibility.

I have seen each of these approaches work for my clients in asserting their innocence.


The Technical Intoxilyzer Approach

Most judges, Crowns, police, and lawyers have very little knowledge about the workings of so-called "approved instruments" and "approved screening devices". Many of these instruments are reliable, most of the time, if they are properly maintained and used according to protocol. Unfortunately some Ontario police officers have ignored the instruments' warranty and serviced their own breath instruments. Unfortunately Ontario police services still use breath instruments considered antiques by their colleagues in the USA. Unfortunately they are not maintained and re-certified in the same manner as hospital equipment. Some have lacked CSA electrical certification in Canada. They are far from infallible. Maintenance records are not always complete. Technical data is often discarded or erased. Some lawyers, judges, and Crowns don't know the distinct functions of the so-called "Intoxilyzer 5000C" and the "Guth 34C". Previously tight control by the Centre of Forensic Sciences over every breath instrument in Ontario has been abandoned. Quality control proposals such as the use of "ADAMS" and "COBRA" data have never been implemented even though the Intoxilyzer 5000C machines were approved by the Alcohol Test Committee as having "communications" capability. Intoxilyzer 8000C instruments are being used by police without a clear understanding by government scientists and police of their environmental and physiological presentation limitations.

Depending on your employment, you may have been exposed to and absorbed a  substance that mimics the ethanol alcohol molecule. If you are a diabetic and/or you didn't eat properly your body may have been producing acetone. These instruments don't handle acetone well, particularly if a local police officer has been adjusting pot voltage settings without an acetone simulator.

Mouth alcohol can falsely elevate breath readings. I have no difficulty blowing over 300 mg/100mLs on my own Intoxilyzer 5000 or on an expert's Intoxilyzer 5000C or 5000EN with a true BAC nowhere near that level. Ontario police officers don't  follow the strict mouth alcohol deprivation periods used by their colleagues in the USA. 8000C's are also subject to mouth alcohol bias.

Room interferent contamination can dramatically affect Intoxilyzer 5000 or 8000 readings without triggering an "ambient fail". I once managed to subtract 80 mg/100mLs from a test result on my own 5000 machine. There are hand cleaners used in some Ontario police detachments that mimic ethanol. I have seen an officer leave a contaminated mouthpiece left on an instrument during an air blank triggering a false zero reference point for the breath tests. I have seen an officer wipe up a liquid on a breathroom floor and then toss the paper towel under the Intoxilyzer triggering bizarre ambient conditions. Ask your lawyer to run experiments using various possible interferents in your home or workplace.

This approach will require your lawyer to consult with experts in other provinces and in the USA. Those experts can be brought to Ontario or video conferencing can permit their attendance in an Ontario courtroom.


The Best Approach

Obviously the best approach is a combination of all these approaches. If your driver's licence or lack of a criminal record is important to your employment then you will want to maximize your chances by asking your lawyer to diligently utilize every one of the above approaches. 





Bill C-32, Bill C-2, and Bill C-46 Notes: 

Parliament has enacted these Bills  in 2008 and 2018 which attempt to abolish the "evidence to the contrary defence".



  • 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 are "approved instruments" in Canada.
  • Alcotest® is a registered trademark of Draeger Safety, Inc. The Alcotest® 7410 GLC is an "approved screening device" in Canada.



List of Young Offenders Debates



Copyright 2018 Stephen Biss



Stephen R. Biss, Barrister & Solicitor

470 Hensall Circle, Suite 303
Mississauga, Ontario
L5A 3V4

905-273-3322  or 1-877-273-3322


Advertisement. Any legal opinions expressed at this site relate to the Province of Ontario, Canada only. If you reside or carry on business in any other jurisdiction please consult a lawyer, solicitor, or attorney in your own jurisdiction. WARNING: All information contained herein is provided for the purpose of providing basic information only and should not be construed as formal legal advice. The author disclaims any and all liability resulting from reliance upon such information. You are strongly encouraged to seek and retain professional legal advice before relying upon any of the information contained herein.