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The "Carter" DUI defence

One of the most popular methods for disputing DUI charges in Canada has been the Carter defence named after the case of R. v. Carter. Carter defences involve testimony and evidence to dispute the intoxication of the accused. While the accused’s BAC reading may be above .08, the Carter defence includes individual, witness, and expert testimony as to factors such as:

  1. the amount of alcohol that was ingested by the accused and in what timeframe;

  2. the accused’s likelihood of intoxication given his or her age, gender, weight, height, and over personal factors.

The purpose of the Carter defence is to meet the definition of “reasonable doubt”. You essentially present to the court that given the amount of alcohol ingested in the period of time prior to the arrest and given the accused’s size, it is doubtfdul that the reading is accurate. Many judges across Canada would acquit individuals based on this contrary evidence being presented in court.

Carter defences require not only testimony of the accused or witnesses to his or her drinking, but also a toxicologist or other medical expert witness. The purpose of the expert witness is to say “he would not have been intoxicated given what he drank”. The two elements are thus testimony that the amount of alcohol the accused ingested on the day or night of the charge combined with expert testimony that the accused would not be legally intoxicated given his or her personal circumstances.

Carter Defence Availability Post 2008

Given the large number of acquittals via this method the Harper government amended the legislation to limit the scope of the Carter defence in 2008. This decision was in reaction to public opinion that drunk drivers were being acquitted too easily. In supporting the legislative amendments, some pointed to judges themselves lamenting that they believed the individual was guilty just not to the standard of “beyond a reasonable doubt”.

Constitutional challenges to the 2008 change

Anytime a government enacts new legislation, there is a possibility that the courts in Canada will find that it violates the Charter of Right and Freedoms and declare it to be invalid. The Charter enshrines numerous rights and principles including the right to a fair trial and to make a defence. Given that the 2008 law prevents or limits certain defences it is thus subject to Charter scrutiny.

As of 2012, several courts across Canada have declared the law to be unconstitutional. This increases the likelihood that the judge hearing a defendant’s case may similarly rule the same way. Lawyers thus may still be able to use the Carter defence in 2012. In cases where trial judges disallow the Carter defence, the defendant may be able to appeal the ruling to the Court of Appeal or the Supreme Court of Canada.

It should be noted that eventually the Supreme Court of Canada will rule on the 2008 amendments and provide clear guidance to courts across the country. If they decide the law is unconstitutional, defendants across the country will have certainty in using this method to dispute DUIs. In response, the Government would likely then enact new, perhaps less restrictive, legislation that they believe will the Supreme Court of Canada will agree with.

What is the current state of the law Ontario in 2021?

The Federal Government of Canada recently amended the Criminal Code to further limit such defences. This being said, these new laws remain largely untested for their constitutionality as of 2021. While the availability and future of Carter type defences is uncertain, it is possible that those disputing DUIs will still be successful using it in 2021. It is important not to discount the possibility of this defence, particularly in cases where the BAC reading is not extraordinarily above .08. Cases can easily take a year or more to reach trial and in that time the new law may be struck down by an Appeal court in your province by the time your matter reaches trial. This would provide certainty of the available of using the Carter defence.

*Please note: The law in Canada regarding DUI defences is constantly changing. It is important to contact a lawyer immediately to determine what defences are currently available options in your particular case.

Call us today.

You don't have to jeopardize your future or waste thousands of dollars on excessive legal fees. We provide effective and affordable lawyer representation for those charged with impaired driving offences throughout Ontario.

Have a skilled criminal lawyer who focuses on impaired driving related charges protect you and your future from the stigma and consequences of a criminal record.

    call us: 647-228-5969


  call us: 647-228-5969


Your case will be defended by a fully licensed Practicing Lawyer of the Law Society of Ontario. For more information about our lawyer, click here.

We provide our clients with:
  • Flat fee pricing
  • U.S. travel advice and information
  • Employment background check advice/services
  • Fingerprints and records destruction services
  • Clear goals of getting charges dropped and bail conditions varied without a trial
  • Help with related immigration issues
  • Vulnerable Sector records suppression help
  • Experienced, focused counsel

* Please note:

If you are not a paying client, we cannot answer questions and provide assistance with U.S. travel, immigration, employment background checks, and avoiding a criminal record. This includes those who have already retained other counsel and those whose cases have already been completed.

Are you a lawyer? If you are defending an impaired driving related case and are looking for expert advice regarding possible defences, case strategies, and information release management call us at: 647-228-5969.

Please note: We do not accept legal aid certificate cases. All clients are handled on a private retainer only.


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  We provide:
  • Flat fee pricing
  • 99%+ non-conviction success rate
  • U.S. travel advice and information
  • Help with related immigration issues
  • Employment background check advice/services
  • Fingerprints and records destruction services
  • A clear goal of getting the charges dropped without a trial
  • Vulnerable Sector records suppression help
  • Timely resolutions
  • Lawyer/client privilege
  • Experienced, focused counsel