It is important to emphasize that many “defences” to impaired driving are simply examples of the prosecutor failing to prove guilt beyond a reasonable doubt, whether due to the exclusion of improperly obtained evidence or because he lacks evidence of guilt. The Criminal Code contains strict requirements for the police in conducting impaired driving or refusal investigations. The prosecution’s failure to prove compliance with any of these requirements can result in you being found not guilty of the charge. Some examples:

  • reasonable and probable grounds by the officer to believe the offence has taken place within the previous three hours;
  • taking samples of breath “as soon as practicable” after the alleged offence;
  • failure to take the first sample within two hours of the alleged offence;
  • proof that the accused was operating a “motor” vehicle;
  • proof that the accused was served with a true copy of the Certificate of Analysis (containing the test results), or notice of the Crown’s intention to rely upon same prior to trial;
  • proof that a “demand” was made;
  • refusal not “unequivocal”;
  • demand not made “forthwith;”

The Charter of Rights protects several important legal rights which arise during any impaired driving investigation. A breach of any of these rights can result in a complete defence to the charges against you. Some of the more common Charter applications are based on the following:

s. 7 – Life, Liberty and Security of Person
Everyone has the right to life, liberty and security of the person and the right not to be deprived thereof except in accordance with the principles of fundamental justice.

Defences under this section often involve errors made in the prosecution of your case. For example, where the prosecutor has failed to provide you with timely disclosure of evidence.

s. 8 – Search or Seizure
Everyone has the right to be secure against unreasonable search or seizure.

This protection has been applied to exclude evidence of impairment and breath testing where the police have failed to show reasonable grounds for their continued investigation. For example, where the arresting officer acknowledges that he did not perform a roadside screening test in accordance with his training, or perhaps chose to rely simply on insufficient symptoms of impairment.

s.9- Arbitrary Detention
Everyone has the right not to be arbitrarily detained or imprisoned.

One example where this protection has been applied is where there has been an unlawful and arbitrary detention of an accused long after he has complied with the breath testing requirements.

s.10 Arrest or Detention
Everyone has the right on arrest or detention: s. 10(a) – to be informed promptly of the reasons therefore; and s. 10(b) –to retain and instruct counsel without delay and to be informed of that right.

Probably most of the Charter cases related to impaired driving area have involved alleged breaches of these rights, particularly those under s. 10(b). Judges recognize that the effective assistance of a lawyer is essential to the proper exercise of all Charter rights, so it is not surprising that they have consistently excluded evidence and dismissed charges where the police have failed to properly respect this particular right.

A few examples where police conduct has resulted in a violation of the section 10(b) right:

  • failure to reasonably allow choice of counsel;
  • failure to provide adequate privacy in consulting counsel;
  • failure to secure an adequate waiver of the right to counsel from the accused;
  • failure to provide a reasonable opportunity to make contact with counsel.

Previously, one of the more common defences to an over .08 charge was “evidence to the contrary.” Typically, this defence involved calling an alcohol expert who provided an opinion that your blood alcohol level should have been under the legal limit at the time of driving, based on what you have told the court about your consumption of alcohol. Recent changes (July 1, 2008) to the Criminal Code have dramatically curtailed this defence. The new legislation, which the government argues is retroactive to offences alleged prior to July 1, 2008, requires the defence to provide evidence that "tends" to show that:

  1. the Intoxilyzer was malfunctioning or operated improperly, and
  2. the malfunction or improper operation caused a reading of over 80 mg, and
  3. the alcohol in the accused’s blood would not in fact have exceeded 80 mg.

Initial results of litigation as to the retroactivity of these provisions have favoured the Crown. This office is currently appealing two such decisions to the Alberta Court of Appeal.

Defence counsel have begun challenging these amendments themselves as contrary to several Charter provisions but few if any cases have been decided at this point. These controversial changes will trigger significantly broader disclosure requests by the Defence as to the training and capability of individual technicians and technical information pertaining to the design, calibration and maintenance of the Intoxilyzer as this information has become essential to mounting the defence..

Other successful defences have involved questioning whether the breath testing equipment has been properly operated or maintained, for example,

  • roadside device being used outside of normal temperature operating parameters;
  • maintenance not being performed within required time periods;
  • failure to take third breath samples where first two test results more than 20 milligrams apart.

In conclusion, the assumption of many that few valid or effective defences exist to an impaired driving allegation is simply incorrect. Only a properly qualified lawyer, familiar with the both the law and facts of your case, can make this assessment.