Responding to certified questions from the Fifth Circuit, the Texas Supreme Court held that in limited circumstances, extrinsic evidence may be considered in determining the duty to defend. Monroe Guar. Ins. Co. v. Bitco Gen. Ins. Corp., 2022 Tex. LEXIS 148 (Tex. Feb. 11, 2022).

The two insurers each provided CGL coverage to the insured, 5D Drilling & Pump Service, Inc., at different times. BIitco provided two consecutive one-year CGL policies covering October 2013 to October 2015. Monroe's CGL policy covered 5D from October 2015 to October 2016.

5D was sued by David Jones for breach of contract and negligence, seeking damage allegedly resulting from 5D's drilling operations on Jones's property. Jones contracted with 5D in the summer of 2014 to drill a 3600-foot irrigation well on his farmland. The complaint did not detail when 5D's purportedly negligent acts occurred or even when 5D began or stopped the work.