Business

What Is Duty to Defend?

A duty to defend is a contractual obligation to defend another party against claims, paying their legal costs as soon as an allegation is made and before fault is decided. It is broader than a duty to indemnify, which applies only once liability is established.

How insurable a duty to defend is depends on the policy. On a commercial general liability (CGL) policy, naming the other party as an additional insured can support it. On a professional liability (E&O) policy there is no additional-insured mechanism, so a promise to defend another party usually means paying their legal bills yourself. Our engineering contract review guide covers the E&O case.

Questions about Duty to Defend?

Our Ontario brokers can explain how it applies to your policy.

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Reviewed by Roughley Insurance Brokers Ltd. — licensed Ontario insurance brokers since 1945. Last updated June 21, 2026. ← Back to the glossary