Court Differentiates Between “Alerted” and “Unalerted” Response Time

Court examined the role of scientific evidence relating to driver reaction time in the context of liability apportionment

In the case WALTER V. PLUMMER, 2010 BCSC 1017 (“WALTER”), released on July 20, 2010, the Court examined the role of scientific evidence relating to driver reaction time in the context of liability apportionment. The case of WALTER dealt with an accident in which the Plaintiff was struck by the Defendant’s motorcycle as he jaywalked across a street near a secondary school.

After largely dismissing evidence purporting to reconstruct the impact some eight years after the accident, the Court held that “of interest, however, and relevant to the assessment of negligence more generally, are the categories of drivers’ states of alertness when measuring perception-response time” (at para. 27).  The Court looked at studies which categorized drivers into “alerted” and “unalerted” groups, and found based on the evidence that alerted drivers (defined as drivers who are expecting or ready for a hazard, although they may not know the precise form it will take) had a reaction time of 0.7 seconds, whereas unalerted drivers (those who are paying attention but not on notice of any untoward hazard) had a reaction time of over 1.0 seconds.

The Court held that “to proceed at 40 kilometres per hour passing a stationary truck in an area known to be frequented by jaywalking students is negligent”, and that in this context the driver was required to proceed in an “alerted state”, as contemplated in the response-time evidence, in order to meet the requisite standard of care.  As the Court found that the Plaintiff had a duty to proceed in an alerted state, it utilized the evidence relating to faster “alert” response times in order to reject the evidence of the Defence which suggested that there was no time for the Defendant to avoid the accident based on an average “unalerted” response time of 1.9 seconds.

The Court ultimately concluded that differentiating between “alerted” and “unalerted” response times “underlines the significance of being alert to possible hazards, something of significance to the negligence analysis more generally” (at para. 28). This holding illustrates how the principles of negligence law can become inextricably linked with the way in which statistical data is approached by courts in a personal injury context.

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