PIERRE, S.D. - A commercial general liability insurance policy's exclusion for an unknown progressive or continuous injury or damage that occurred before the inception date is not void by public policy, the South Dakota Supreme Court held April 16, affirming summary judgment to an insurer regarding claims for shared defense costs of a mutual insured in an underlying construction defect case (AMCO Insurance Co. v. Employers Mutual Casualty Co. d/b/a EMC Insurance Cos., No. 26797, S.D. Sup.; 2014 S.D. LEXIS 23).