A general contractor brought an action against the subcontractor's commercial general liability insurer alleging that the insurer breached its duty to defend and indemnify the general contractor as an additional insured. This case is Tri-Star Theme Builders, Inc. v. OneBeacon Insurance Company, 426 Fed.Appx. 506 (2011).

 Tri-Star, the general contractor on a resort and casino project subcontracted the plumbing and HVAC work to Golden West Mechanical. Golden West agreed to make Tri-Star an additional insured under its commercial general liability policy. The additional insured endorsement included Tri-Star as an additional insured, but only with respect to liability arising out of Golden West's ongoing operations and only to the extent of liability arising out of Golden West's negligence.

 After the completion of the project, the owner of the casino filed a complaint against Tri-Star alleging that there were substantial and material defects in the design and construction of the resort. Some of the damages obviously arose out of the plumbing and HVAC systems so Tri-Star sought coverage as an additional insured under the policy issued by OneBeacon. The insurer denied any coverage and Tri-Star sued. The trial court ruled in favor of the insurer and this appeal followed.