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 new trial.
    • 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?