When the police have reasonable suspicion of drunk driving, for example, when a driver engages in improper turning, weaving or erratic braking, they can stop the vehicle. After the driver stops, the officer will typically look for further evidence, such as odors of alcohol, bloodshot eyes or an open container of alcohol inside the vehicle.
They may then request to perform a preliminary breath test (PBT) on the roadside to establish probable cause for arrest. If they arrest the driver, they will have them perform an evidential breath test at a police station or hospital, which is subject to Michigan’s Implied Consent Law penalties.
But, how accurate are the breathalyzers used in these tests?
They are designed to be accurate
Breathalyzers are generally reliable for estimating blood alcohol concentration (BAC). For law enforcement use, manufacturers design breathalyzers to meet strict precision standards. Manufacturers also often use advanced technology, such as fuel cell technology, to ensure these devices are stable and reliable.
Nonetheless, they have to be calibrated to remain accurate. Regardless of design and technology, a breathalyzer’s sensor loses its sensitivity over time. Repeated exposure to alcohol, environmental contaminants and humidity results in chemical degradation in the sensor. This can lead to false positives and inaccurate BAC readings.
A certified operator must calibrate sensors regularly against a known alcohol standard to ensure readings are within Michigan’s standards.
Other things can affect them
Readings can be affected by some other things. These include mouthwash, breath sprays, fermented foods, medical conditions like acid reflux, medications and aceton, which is increasingly produced by individuals on keto/low-carb diets or with diabetes.
If you believe that your BAC reading was inflated, consider legal guidance to explore your defense options.