# State v. Copeland

State v. Copeland, 130 Wn.2d 244, 270, 922 P.2d 1304 (1996), involving RFLP typing, the Court concluded that the product rule for establishing statistical probabilities of a genetic profile in the human population is generally accepted within the scientific community, and therefore the product rule is admissible for determining the probabilities of a random match.
The product rule (or "multiplication rule") as applied in RFLP typing means that the probability of a genetic profile occurring in the population is the product of the probabilities of each individual allele's occurrence in the population.
Validity of the rule depends upon whether the individual alleles are actually statistically independent. . . . Two assumptions underlie use of the product rule when calculating genetic profile frequencies: linkage equilibrium, which means that the alleles at different loci are inherited independent of each other, and Hardy-Weinberg equilibrium, which means that one allele at a locus is not predictive of the other allele at that locus (one allele is inherited from the mother, the other from the father). Hardy-Weinberg equilibrium depends upon an assumption of a large population in which there is random mating. Copeland 130 Wn.2d at 264-65.