This essay proposes a ten‐step recipe for applying California's nearly unique—"comparative impairment"—choice‐of‐law rules. The formula is elaborated for environmental insurance claims, placed in the context of leading California cases, and compared and contrasted with the principal choice‐of‐law approaches in other jurisdictions and as set forth in the All'sComplex Litigation Project.It is suggested that, as a practical matter, the customs and traditions of choice‐of‐law legal argumentation require explicit reliance on theoretical—impractical looking—academic sources.