One of the available defences to an action in negligence in the motor vehicle collision context is for a defendant to show that the collision was an inevitable accident.

The traditional test for the inevitable accident defence was established in McIntosh v Bell :

… a person relying on inevitable accident must [show] that something happened over which he had no control, and the effect of which could not have been avoided by the greatest care and skill.

The test requires a defendant to show two things: (1) the external event occurred without any input or contribution from the defendant (i.e. it was out of his control and unforeseeable); and (2) the resulting collision, could not have been avoided by the greatest use of care and skill.

The application of the test is, however, dependent on the facts of each case. Therefore, whether a defendant can establish that an accident was inevitable is dependent upon the circumstances of the accident.

Most often, the defence is raised in situations of slippery or icy road conditions. However, it is only in rare circumstances that the defence will be successful.

Some Examples

In 1969, the British Columbia Court of Appeal was asked whether a defendant was careless in the manner of driving his vehicle or whether he could explain that the skid on an icy patch of road, that led to the collision in question, could have occurred in absence of his negligence. The Court of Appeal held that the defendant would have to show: (1) he did not expect ice at that point of the road; and (2) that he had no reason to expect it. However, the Court of Appeal also reasoned that if the defendant could have foreseen the possibility of icy road patches, he was bound to drive slowly enough to avoid these:

In short the respondent’s evidence did not provide any explanation of how his car may have skidded without any negligence on his part. He did not know what caused his car to skid; he considered his speed of 25 to 30 m.p.h. at that point safe under the prevailing conditions. It is clear that he was simply driving too fast to keep control of the car on the ice that he ought to have expected. No jury properly instructed could have reasonably found that the respondent was not negligent…

Similarly, the defence of inevitable accident was rejected in New Brunswick where the New Brunswick Court of Queen’s Bench found that:

[the] defendant Sullivan was driving too fast on very slippery and dangerous road conditions which ought to have been reasonably apparent on this blustery, cold night while attempting to navigate a corner and a knoll and that this was the reason he lost control, went off the highway and cleaned off the telephone pole… In my view these circumstances cannot be said to describe “an accident that could not possibly have been prevented by the exercise of ordinary care, caution and skill.

Here in Alberta, in Borthwick and Borthwick v Campa, the Alberta Court of Queen’s Bench allowed the defence to defeat an action in negligence. The defendant came across a patch of black ice that was a complete surprise as the road conditions were not at all indicative of any possibility that ice may have formed anywhere on the road. Further, Police officers testified that the existence of black ice at that location was a surprise and that it was localized and extended across the highway. The defendant denied liability, claiming inevitable accident. In allowing the defence, the Court made the following comment:

In effect, what these cases and the cases cited by the defendant establish is the simple principle that where one encounters unexpected and unforeseeable conditions and an accident occurs, the fact that an accident occurs does not necessarily establish a lack of competence to the point of negligence on the part of the individuals whose driving conduct is in question… On all of the evidence before me, I am satisfied that the existence of black ice at or near the place of the accident was an unforeseeable condition. The driving habits and patterns of the defendant driver were consistent with those of a reasonable and competent driver and there is no evidence whatsoever that establishes any lack of reasonable skill or aptitude in this driving pattern both before and upon encountering the black ice which would lead to a finding of negligence against him. In effect, this tragic and unfortunate accident was occasioned, I am satisfied on the evidence before me, without any negligence whatsoever on his part.

In conclusion, the inevitable accident defence will operate to defeat a negligence action in circumstances where the facts align to conclusively demonstrate that the actions of the defendant were reasonable and that the external event which contributed to the collision was totally unforeseeable and consequently, the collision was inevitable.