Interpreting an additional insured endorsement, the Court of Special Appeals of Maryland recently held that the use of the phrase “caused, in whole or in part, by” triggered the insurer’s duty to defend claims alleging negligence by its named insured, its additional insured, or both. James G. Davis Constr. Corp. v. Erie Ins. Exch., 126 A.3d 753 (Md. Ct. Spec. App. 2015) (No. 802). As part of the underlying action, James G. Davis Construction Corp. (“Davis”) served as the general contractor on a home construction project in Washington, DC, and entered into a subcontractor agreement with Tricon Construction, Inc. (“Tricon”) for certain discrete service work. Pursuant to the subcontractor agreement, Davis was included as an additional insured on a commercial general liability policy issued by Erie Insurance Exchange (“Erie”) to Tricon as the named insured. The additional insured endorsement in that policy provided coverage for injuries “caused, in whole or in part, by” (i) Tricon’s acts or omissions or (ii) the acts of omissions of those acting on Tricon’s behalf. Both Tricon and Davis were later sued in a personal injury action, alleging that each had been negligent in connection with faulty worksite scaffolding erected by Tricon and approved by Davis. Using its additional insured status, Davis sought coverage from Erie under the policy issued to Tricon. Erie denied any duty to defend or indemnify, arguing that Davis was not entitled to additional insured coverage for its own negligence. Reversing the lower court’s decision in favor of the insurer, the Court of Special Appeals held that the use of the phrase “caused, in whole or in part, by” in the policy’s additional insured endorsement broadened the coverage available to Davis, as compared, for example, to the use of a phrase like “arising out of.” The former phrase could include liability proximately caused, while the latter phrase could be limited to liability vicariously caused. As a result, the insurer’s duty to defend Davis was not limited to claims of vicarious liability dependent upon Tricon’s acts or omissions, and instead, was triggered by the acts or omissions ofeither its named insured (Tricon), or its additional insured (Davis), or both. Since the complaint alleged negligence by both Tricon and Davis contributed to the underlying accident and injuries, Erie was obligated to defend, and potentially indemnify, both of them in response to the underlying action.