Was Your Breathalyzer Test Fair?: Understanding the Residual Alcohol Defence

When an officer suspects a driver of driving over the legal alcohol limit, they will often administer a breathalyzer test to get a quick reading of the driver’s blood-alcohol content (BAC). However, for every advantage of this method there are equally as many flaws. As criminal defence attorneys in the Vancouver Area, we have seen many drivers operating their vehicles at well within the legal range still be charged with a crime that could have severe consequences on their lives. When it comes to DUI charges, it’s important for you to understand the concept of residual alcohol in the mouth.

Discussions on drinking and driving laws often centre around the ability of police to accurately test a driver on the side of the road. For a charge with such severe repercussions, the method of testing a driver is notoriously unreliable. This has led to many innocent drivers on BC’s roads being charged with severe crimes. Drivers well within the legal limits can be charged with a DUI simply because they had residual mouth alcohol.

This blog provides more on the concept, the officer’s responsibilities, and how the residual alcohol defence can benefit innocent drivers.

Understanding Residual Mouth Alcohol (RMA)

Residual mouth alcohol is the leading cause of inaccurate readings for roadside breathalyzer tests, one of the main reasons being how common it is. Several things can cause RMA. Evidently, consuming alcoholic beverages is one, but also chewing tobacco or even blood within the mouth can also produce an improper reading. Since the breathalyzer is designed to detect alcohol-laden blood that passes through the sacs in your lungs (and is then measured via your breathe), the extra RMA can enter your breathe as it passes through your mouth and produce an inaccurate reading.

A Quick Example: You’ve gone to the bar with friends and enjoyed your favourite craft beer. It’s strong and full of taste, but you are far within your legal limit to drive. Right down the road is a DUI checkpoint, and the officer can smell the strong scent of the beer since it was potent and you just drank it. Your breathe produces a reading showing that you are over the limit since the RMA was present in your breathe. You now have a DUI charge despite being within the legal limit.

Police Make Mistakes

To combat instances of RMA affecting innocent drivers, the law requires officers to wait before administering the test. Officers are normally instructed to wait 15 minutes before giving you your exam. However, studies have shown that RMA can remain in the mouth far longer than that, and we all know that officers are prone to mistakes from time to time (who isn’t?).

The Residual Mouth Alcohol Defence for DUIs

The justice system understands the flaws with the breathalyzer method for taking readings and proving a driver was above the legal limit for alcohol, so if there’s any doubt that can be cast on your charge, there is a good chance it will weigh heavily into the court’s decision. Even a single drop of RMA can produce a falsely high reading.

Did You Know?: Were you aware that some soy sauces even contain alcohol? So eating a roll of sushi puts you at risk, too.

We in no way condone drunk driving, but as criminal defence attorneys, it is our duty to defend innocent Canadians from unfair charges. If you think that residual mouth alcohol caused your DUI, you must contact a DUI attorney in Vancouver immediately. A DUI charge on your record will have serious negative implications on your life.