Logical relevance: problems with the reference population and DNA mixtures in People v. Pizarro

The concept of relevance is fundamental to the law of evidence. A California court of appeals recently invoked this concept to deem inadmissible estimates of the relative frequency of an incriminating DNA type in major racial groups and computations relating to a mixture of DNA from more than one person. This article shows that these statistics are relevant evidence because they help the factfinder assess the significance of matching DNA types under various hypotheses that might be entertained about the origin of the DNA samples.