The invention is a method and system useful in determining the degree of comparative negligence of an insured person involved in an accident as compared to the comparable negligence of other parties involved in the accident, in particular the insurance claimant. The method and system of the invention include, at a minimum, the steps of gathering preliminary information concerning accident type, applying preliminary rules to the preliminary information to determine accident type, gathering additional information specific to the accident type, and applying accident-type-specific rules to the additional information to determine the degree comparative negligence of said insured person and/or the claimant.