Similar Fact Evidence in Workplace Disputes

You likely read about charges against the former Attorney General of Ontario, Michael Bryant being dropped this week.  Bryant killed a cyclist who grabbed onto his car and was killed when he hit a pole after flying from the moving car.  What does this have to do with employment and labour law, you ask?
Well, this.  If you read the prosecutor’s explanation of why the charges were dropped, much turned on the fact that the cyclist had had several earlier similar run ins with other drivers.  In fact, there were six such incidents referred to. Just think about that for a second.

Does the fact that the cyclist has a history of confronting drivers (sometimes aggressively) prove that Bryant is innocent of recklessly driving him into a pole that evening?

The answer is clearly “no”.  Bryant still might have overreacted on the particular night in question and be guilty of a crime.  But the evidence of the cyclist’s past certainly makes him look like a dangerous psycho, which would certainly effect how a jury would think about what happened.
So the question is, when should evidence about someone’s past behaviour be used to show that the person probably behaved in that way again?  This is called “similar fact evidence“.  And it does come up in employment cases.
Here’s an example involving a City of Kitchener fire fighter who was dismissed for alleged sexual harassment of a female subordinate.  He was fired for a series of incidents, but the main one involved him (allegedly) leaning his, er, parts into the female’s back.  He denies this happened.  At the arbitration, the employer put the female employee on the witness stand, and when the union was cross-examining her, it attempted to ask questions about a domestic dispute in which she had made allegations against her  then fiance.
The union argued that the evidence of what she told police in the domestic dispute was very similar to the lie she made up against her boss:  in both cases, she is alleged by the union to have lied about what the man had done to her, both involving “phallic” references.   So the union alleged there is a pattern of similar behaviour that was relevant to whether she was telling the truth about what happened to her at work.  She lied before, and she is lying again.
The employer objected to the line of questioning about the domestic dispute, and the arbitrator did not allow that evidence to be called.  The arbitrator relied on statements of the rules of similar fact evidence by the Supreme Court of Canada and other arbitrators, including this summary by Arbitrator Surdykowski:

It is clear that evidence of conduct on other occasions which tends to suggest a mere propensity to engage in a particular type of conduct or to show a general disposition … is not admissible to prove the commission of a subsequent act.  So, for example, a plaintiff…in an assault case cannot be asked in cross-examination about the fights he has been in order to show a propensity to fight.

But sometimes, the behavour in question is so unusual that to do it more than once does tend to suggest strongly that the person does that sort of thing.  So courts and arbitrators have created a balancing test, as explained by the Supreme Court:

There will be occasions, however, where the similar act will go to more than disposition, and will be considered to have real probative  value.  That probative value usually arises from the fact that the acts compared are so unusual and strikingly similar that their similarities cannot be attributed to coincidence. Only where the probative force clearly outweighs the prejudice, or the danger that the jury may convict for non-logical reasons, should such evidence be received.

So in the firefighter case, the arbitrator ruled that the two incidents–one involving workplace harassment and one involving a violent domestic dispute–were not so strikingly similar to justify allowing that evidence into the hearing.  [The case then proceeded and the Grievor was reinstated with a demotion and a penalty of 20 shifts unpaid].