Breathalyzer test results are the most critical evidence the Crown uses to secure convictions in Canadian DUI cases that hinge upon blood alcohol concentrations (BAC). According to the Criminal Code, Canadian courts are required to treat breathalyzer readings as “conclusive proof” of a driver’s BAC, with levels over 80 mg of alcohol in 100 mL of blood serving as the threshold needed for conviction.
However, breathalyzer devices, such as the infrared spectrometry-based unit “Intoxilyzer” used by most Canadian police services, are not infallible, nor are the police officers and technicians responsible for following the technical breathalyzer calibration procedures required by the Criminal Code.
Thus, if there is any hint of Intoxilyzer calibration problems, defense lawyers strive to challenge them to secure case dismissals, withdrawals, stays, acquittals, reduced charges, or other favourable outcomes.
The first thing to know about breathalyzers is that there are distinct differences between the devices and procedures used during roadside screening and at the police station. Section 320.27 of the Criminal Code authorizes police to stop and screen any driver for potential alcohol impairment with an approved screening device (ASD). These roadside screening devices are not as accurate as in-station Intoxilyzer-type ones, and their results cannot be used as evidence in court. Instead, ASDs are used to determine whether a driver should undergo further testing with an in-station breathalyzer machine.
Drivers do not have the right to consult with a lawyer before undergoing roadside ASD screening, and refusing a breath test is a Criminal Code offence that carries similar penalties to a standard DUI charge. Drivers who pass ASD screening with a reading below 0.05% BAC are typically allowed to continue their journey, while those who register fail readings above 0.08% are arrested for DUI and taken to the police station for breathalyzer testing. While federal law does not allow this DUI breath-test admissibility, Ontario law allows ASD readings between 0.05% and 0.079% (the warning range) to be used to impose administrative penalties, including include fines, short-term license suspensions, vehicle impoundment, and other sanctions.
If brought to the police station for breathalyzer testing, the first thing you should know is that you have the constitutional right to consult with a lawyer before undergoing the testing. However, you do not have the legal right to refuse to blow into the breathalyzer subsequently. If you fail to undergo breathalyzer testing, police will charge you with refusing to comply with mandatory breath testing, which carries similar penalties as a standard DUI.
Section 320.31 of the Code requires breathalyzer-certified police to conduct calibration exercises before a driver undergoes breathalyzer testing. These include:
After calibration and a 15-minute driver observation period, the police breathalyzer technician conducts the first breath test in which the driver is required to blow into the machine’s mouthpiece with a long, consistent exhale of at least six to 10 seconds. This exhalation is designed to capture breath from the lungs rather than the mouth, and the breathalyzer’s testing chamber uses infrared spectrometry to measure the ethanol concentration in the sample. The breath ethanol amount is then used to calculate the equivalent BAC.
The Code requires police to secure a second breath sample after a 15-minute interval following the successful collection of a first sample. The lowest BAC reading of the two samples is allowed to be introduced as Crown evidence to prove impairment. However, the two test results cannot differ by more than 20 mg of alcohol in 100 mL of blood.
As noted, breathalyzer machines and their technicians are not infallible, and DUI defence lawyers strive to expose technical and procedural problems that can raise reasonable doubts about the veracity of the breath evidence. When successful, such challenges often lead the court to exclude the evidence, which can result in dismissed charges and other favourable outcomes. Typical defence challenges to breathalyzer testing include:
By examining breathalyzer maintenance records, a DUI lawyer may be able to expose historic device malfunctions that call into question the accuracy of the device’s BAC results. However, such maintenance records are not automatically included as part of the Crown’s disclosure of breathalyzer data, which Section 320.34 of the Code sets out as:
The defense can petition the court for such disclosure, provided it can prove in a hearing that the maintenance records have relevance in “determining whether the approved instrument was in proper working order.”
The Greater Toronto Area DUI defence lawyers at Mass Tsang have an exceptional record of successfully challenging breathalyzer results. Their legal team is highly adept at uncovering technical and procedural errors in breathalyzer testing, resulting in numerous case dismissals for their clients. To learn how these legal experts can strategize a solid defence against your DUI charges, schedule a free consultation by contacting us today.
A: Breathalyzer calibration verifies the device’s accuracy by testing a certified alcohol standard sample, with the device required to deliver results within a 10% range of the target value. Proper calibration is crucial in DUI cases because it supports breathalyzer results as being conclusive evidence of a driver’s blood alcohol concentration at the time of testing.
A: Absolutely. Section 320.16 of the Criminal Code does not allow courts to consider breathalyzer readings as “conclusive proof” of blood alcohol concentrations if the defence can prove that the device has not been properly calibrated or maintained.
A: Ontario Police follow Criminal Code and Canadian Society of Forensic Science Alcohol Test Committee standards in maintaining and calibrating their breath testing devices. In-station breathalyzer machines undergo calibration checks using an approved alcohol standard before each breathalyzer test of an impaired-driving suspect. Police calibrate approved roadside screening devices every 14 to 31 days, depending on the manufacturer’s recommendations and required standards.
A: The Criminal Code requires breathalyzer calibration testing to come within 10% of the certified alcohol test subject target value. During actual breathalyzer testing, the driver’s duplicate breath samples must agree within a 20 mg/100 mL range.
A: Diabetes, gastroesophageal reflux disease, and asthma can affect breathalyzer results, and skilled DUI lawyers have successfully challenged breathalyzer results affected by these conditions.
A: Documentary evidence that may help prove that a breathalyzer was improperly calibrated includes:
A: While there are no Criminal Code or provincial mandates for retaining breathalyzer maintenance records, most police agencies retain such records for at least five years after the decommissioning of a device.
