# Discovery Rule

> A legal principle that delays the start of the statute of limitations until the plaintiff discovers or reasonably should have discovered the injury and its cause.

**Category:** Legal Procedure
**Canonical URL:** https://drugsmonitor.com/glossary/discovery-rule
**Last updated:** 2026-06-11

The discovery rule is particularly important in pharmaceutical cases where injuries may take years to develop after exposure. Under this rule, the statute of limitations clock starts when the plaintiff knew or should have known that the drug caused their injury.

What constitutes reasonable discovery varies by state and case facts. Some courts look at when the plaintiff received a diagnosis, when a link was first suggested by a physician, or when public information about the drug's risks became available.

The discovery rule creates factual disputes about when the limitations period began. Defendants often argue that the plaintiff should have discovered the connection earlier. Your attorney can explain how your state applies the discovery rule to your case.

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*Glossary entry from DrugsMonitor.com.*