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Similar Daubert v Merrell Dow Phar, Jaffee v Redmond, Abel v United States, Griffin v California | ||
People v. Collins was a 1968 American robbery trial noted for its misuse of probability and as an example of the prosecutor's fallacy.
Contents
Trial
After a mathematics instructor testified about the multiplication rule for probability, though ignoring conditional probability, the prosecutor invited the jury to consider the probability that the accused (who fit a witness's description of a black male with a beard and moustache, and a Caucasian female with a blonde ponytail, fleeing in a yellow car) were not the robbers, suggesting that they estimated the odds as:
The jury returned a guilty verdict.
Appeal
The California Supreme Court set aside the conviction, criticising the statistical reasoning for ignoring dependencies between the characteristics, e.g., bearded men commonly sport moustaches. The court asserted that mathematics, "...while assisting the trier of fact in the search of truth, must not cast a spell over him."