Symptoms from the Consumption of Alcohol

When alcohol is consumed it can have effects that are both observable and unobservable. Most of the observable effects are familiar to people, and are associated with intoxication. These include defects in speech and balance. For example, you may start to slur your words while speaking, or you may develop poor balance with a stumbling or weaving gait while walking, and these can be readily noticed by police officers. The unobservable effects of alcohol include delays in reaction times, as well as decreases in comprehension, attention, and judgement. These are the effects which cause impairment. When a driver is impaired by alcohol, the risk of a crash increases as the BAC rises. Most scientists agree that all drivers are impaired at BACs of 80mg% or more, and many drivers are impaired at lower BACs.

Impairment occurs at lower BACs than intoxication. Everyone starts becoming impaired at BACs in the range of 20 – 80 mg%, but there may be few, if any, observable symptoms at this range. Often, you can’t look at a person and see that they are impaired. However you can see when someone is intoxicated by alcohol; for the average social drinker these observable effects on speech and balance start to occur at BACs of about 150 mg%. Therefore if a person is slurring and has balance problems because of alcohol in their blood, then we can conclude they are both impaired and intoxicated.

The number and severity of symptoms (both observable and unobservable) increases along with a person’s BAC, but there can be significant differences in the presentation of symptoms for different individuals. People who regularly become intoxicated, or who regularly consume large amounts of alcohol, may develop a tolerance to alcohol. Such a drinker may require a higher BAC to exhibit the same symptoms that an average social drinker exhibits at a lower BAC. Conversely, a person who drinks alcohol infrequently may show intoxication symptoms at lower BACs than the average social drinker.

Other observable effects from alcohol might include an odour of liquor (depending on the type of alcohol consumed), watery eyes, flushed face, and bloodshot eyes. These effects can occur at much lower BACs than the speech and balance effects, and can appear in some people at BACs less than 80 mg%. These other observable effects become more common as the BAC rises, but sometimes may have causes other than the consumption of alcohol and therefore may occur in people who are neither impaired nor intoxicated.

Police are trained to make careful observations of suspected impaired drivers and to record any symptoms of alcohol consumption or poor driving in their notebooks and in any narrative describing an incident. The police narrative is one of the important documents to be considered by the RoadSafetyBC adjudicator during the IRP review. Poor driving, difficulty producing documents, or speech and balance problems are often seen as evidence corroborating high BACs and an ASD FAIL, while a lack of these symptoms may be consistent with lower BACs.