The Fourth Appellate District reversed a decision of the superior court appellate division. The court held that the trial court erred in excluding expert testimony regarding the purported unreliability of blood alcohol breath tests based on the trial court erroneous assumption that the proffered evidence was inadmissible partition ratio evidence.

Terry Vangelder was tried before a jury on charges, among others, of driving with 0.08 percent or more by weight of alcohol in his blood and speeding.