This Simpson Thacher & Bartlett LLP memorandum discusses recent court rulings on pro rata allocation, the meaning of "irritant" under a pollution exclusion, the scope of director and officer (D&O) liability insurance, medical monitoring claims under a general liability policy, use of extrinsic evidence in determining an insurer's defense obligations, and coverage under an "additional insured" provision in a contractor or sub-contractor's general liability policy. The memo also discusses court rulings on the availability of excess coverage where a policyholder settles with a primary insurer for less than the policy limits, and New York's bond posting requirement for non-resident plaintiffs.