Emhart Industries sued its insurance carriers for refusing to defend and indemnify costs related to environmental contamination cleanup at a Superfund Site. The court ruled that insurers must defend their policyholders whenever charging documents allege facts that could potentially fall within policy coverage, even if those facts are ambiguous or remote. The insurer bears the burden of proving there is absolutely no potential coverage to avoid the duty to defend. This matters to subcontractors because it means your general liability insurer likely owes you a defense in environmental or pollution claims unless they can definitively prove the policy excludes that type of damage.
If a lawsuit or claim alleges facts that could possibly be covered by your insurance policy, the insurer must pay for your legal defense—even if coverage is unclear or unlikely.
The burden is on the insurance company to prove there is zero chance of coverage; you don't have to prove coverage exists to get a defense.