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What defences may be used against a charge of impaired driving?

Region: Ontario Answer # 7714

Although a charge of impaired driving has significant legal implications, it is important to note that an impaired driving charge is not the same as a conviction. There are legal defences that can be employed to challenge the charges that could possibly lead to a reduction or even a dismissal of the charges. If you have been charged with a criminal driving offence such as impaired driving, it is important to hire an experienced criminal defence lawyer as soon as possible.

Different defences that may be used to fight an impaired driving charge include:

  • The traffic stop was unlawful
  • The testing methods were faulty or had errors
  • The police officer’s observations are unreliable or not credible

Unlawful traffic stops

Police can lawfully stop vehicles for many reasons, for example to check for a driver’s licence, vehicle registration or proof of insurance, at a Sobriety Spot Check, for erratic driving, or for equipment violations such as burnt-out taillights and headlights.

If police see a driver commit any sort of Highway Traffic Act violation, such as speeding or failing to signal, they can pull the driver over and they can conduct a sobriety / breath test on the driver. Specifically, mandatory alcohol screening under section 320.27(1) of the Criminal Code authorizes police officers to demand that a driver provide a roadside breath sample on an approved screening device without reasonable suspicion that the driver has alcohol in their body, but only after the person has been lawfully stopped.

If it can be demonstrated that a traffic stop was made unlawfully, any evidence obtained during the stop, including field sobriety test results and chemical test results, could potentially be deemed inadmissible in court.

Challenging impaired driving testing methods

In Canada, law enforcement officers use a variety of tests to assess impairment in drivers suspected of impaired driving offences such as breathalyzer tests, bodily fluid and blood tests, and Standardized Field Sobriety Tests. Each of these testing methods can potentially present inaccuracies or errors, providing grounds for a legal challenge in an impaired driving case. Some of these errors could include:

Breathalyzer test errors: The breathalyzer devices must be properly maintained, calibrated, and administered by a trained professional to ensure accurate results. Additionally, external factors such as mouth alcohol, certain medical conditions, or use of certain medications can also potentially affect the test results. As well, if the police failed to conduct a breathalyzer test within the legally prescribed time limit, or if they failed to inform the accused of their right to a second test on a different instrument, this could potentially lead to the test results being excluded from evidence.

Blood test errors: Blood tests can be subject to contamination, incorrect handling, or lab errors. Additionally, police must follow a strict protocol in collecting, storing, and testing the blood samples.

Field sobriety test errors: The reliability of field sobriety tests can be influenced by factors such as the individual’s physical condition, weather conditions, or even the footwear the person is wearing at the time of the test.

Challenging the arresting officer’s observations

A police officer’s observations play a crucial role in impaired driving cases. One common argument is that the officer lacked the necessary grounds to make the initial stop or demand a drug test. Although on officer can conduct a breath test without reasonable suspicion that the driver has alcohol in their body, to demand an oral fluid sample, police must have a reasonable suspicion that the driver has drugs in their body, for instance because the driver has red eyes or muscle tremors or appears agitated.

The officer’s observations are typically documented in their notes and may be presented as evidence in court. However, an officer’s observations are inherently subjective and may be influenced by a variety of factors, including the officer’s training, experience, biases, or even the stress of the situation.

The defence may challenge the officer’s reliability and interpretation of their observations. For instance, certain medical conditions or physical disabilities may affect a person’s speech or balance, potentially leading to misinterpretations of impairment such as during a Standardized Field Sobriety Test.

Furthermore, observational evidence can be challenged on the grounds of reliability. For example, poor lighting conditions during a nighttime stop may affect an officer’s ability to accurately observe signs of impairment. Similarly, certain smells that officers associate with drug use can also come from legal substances or can linger in a vehicle long after use.

If the defence can cast doubt on the accuracy or credibility of the officer’s observations, this could potentially weaken the prosecution’s case.

What is an Affirmative Defence?

In Canadian law, affirmative (or true) defences refer to arguments that, even if the prosecution’s allegations are true, justifying or excusing circumstances (mitigating factors) exist that should prevent conviction. In impaired driving cases, commonly employed affirmative defences include:

  • Necessity: refers to situations where the accused had no reasonable choice but to drive under the influence, to prevent a greater harm.
  • Duress: refers to situations where the accused was compelled to drive under the influence due to threats or force from another person.
  • Entrapment: a less common defence, could be argued if law enforcement officials induced an individual to commit an offence that they would not have otherwise committed.

Affirmative defences are not applicable in every case and are often dependent on the specific circumstances surrounding them. They typically require the defendant to admit to the offence, but to also provide additional evidence that justifies or excuses the behaviour.

For instance, the defence of necessity might be invoked if a person, needing urgent medical attention and having no other means of transport, chose to drive while impaired. For a duress defence, evidence of threats or force that compelled the accused to drive while impaired would be needed. For entrapment, there would need to be evidence of improper government action that led to the offence.

Importance of legal representation in impaired driving cases

While the question of how and when these defences can be used varies widely depending on the specific circumstances of each case, having experienced legal representation can significantly influence case outcomes. This could include a reduction or dismissal of charges, lighter sentencing, or alternative resolutions such as treatment programs.

Get help

To erase your criminal record, call toll-free 1-888-808-3628 or learn more at Pardon Partners. It’s easier than you think.

If you have been charged with a driving offence, it is important to hire an experienced criminal defence lawyer as soon as possible. Contact our preferred criminal defence expert, Calvin Barry Criminal Lawyers for a free consultation at 416-938-5858 .

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