People v. Collins 68 Cal.2d 319, 66 Cal.Rptr. 497, 438 P.2d (1968)
Collins and his wife were accused of robbery.
Collins was a black man with a beard and his wife was a
blond white woman.
At Trial, the prosecutors had difficulty establishing a
positive identification, so they resorted to probabilistic evidence.
Basically, they brought in a math professor as an expert
witness to say that since witnesses claimed that the crime was
committed by a 'black man with a beard and a blond white woman' there was
an overwhelming probability that the crime was committed by any couple
answering to such distinctive characteristics.
Only 1 in 12 million couple share these characteristics.
The Trial Court found Collins guilty. He appealed.
The California Supreme Court reversed and remanded for a
The California Supreme Court found that guilt cannot be
determined by odds, and that the introduction of probabilistic
evidence infected the case with fatal error.
The testimony itself lacked an adequate foundation in
both evidence and statistical theory.
The expert appeared to have pulled the statistical
evidence out of his butt.
The testimony distracted the jury from its proper
function of weighing evidence on the issues and made them rely upon an
irrelevant mathematical demonstration.
Basically, even if you could prove that few couple met the
description, this evidence has no relevance as to whether or not
Collins and his wife committed the crime.
What if the true criminal was wearing a fake beard? How
would that skew the statistics?