What legal principle requires full disclosure of all material facts by the insured?

The legal principle requiring the insured to disclose all material facts is utmost good faith, also known by the Latin phrase uberrimae fidei.

Insurance underwriting depends heavily on information supplied by the applicant. A material fact is one that could influence an insurer’s decision to accept the risk, set the premium, or impose terms. Concealing a serious pre-existing condition, a hazardous activity, or another important circumstance can therefore affect whether a policy is issued or later challenged.

The principle is broader than ordinary honesty in everyday contracts, although it is not identical to the separate concept of materiality. “Good faith” is a general legal standard; “utmost good faith” identifies the heightened insurance duty traditionally associated with disclosure by the applicant and fair dealing by the insurer.

Its application varies by jurisdiction, policy type, and governing law. Marine insurance and reinsurance are classic contexts in which the doctrine is emphasized. Modern statutes and policy language may modify its consequences, so nondisclosure does not automatically produce the same result in every insurance dispute.