eight corners rule
eight-corners rule. Insurance. The principle that a liability insurer’s duty to defend its insured — generally triggered if the plaintiff’s claims against the insured are within the policy’s coverage — is assessed by reviewing the claims asserted in the plaintiff’s complaint, without reference to matters outside the four corners of the complaint plus the four corners of the policy. — Also termed allegations-of-the-complaint rule. Cf. FOUR-CORNERS RULE . [Cases: Insurance 2914, 2915. C.J.S. Insurance § 1150.]
