Interim Ceiling Principle
In State v. Jones, 130 Wn.2d 302, 308-11, 922 P.2d 806 (1996), we explained that the interim ceiling principle was recommended in COMMITTEE ON DNA TECHNOLOGY IN FORENSIC SCIENCE, DNA TECHNOLOGY IN FORENSIC SCIENCE 92 (National Academy Press 1992) to account for the possibility of substructuring in human populations.
It was never intended to be scientifically precise, but was intended to provide an interim, conservative method for calculating a random match probability.
In Jones, 130 Wn.2d at 311, the Court noted that the method was "widely accepted, given its admitted limitations," and rejected the defendant's claim that the interim principle was not generally accepted in the scientific community.
As the Court predicted in Jones, use of the interim ceiling principle has declined substantially (if not completely) in the wake of a new report, COMMITTEE ON DNA FORENSIC SCIENCE: AN UPDATE, THE EVALUATION OF FORENSIC DNA EVIDENCE (National Academy Press 1996), which concluded that product rule calculations are appropriate, id. at 122-23, and rejected the ceiling principles, id. at 156-59.