US-CaliforniaWhat is the discovery rule for medical malpractice statutes of limitation?
In California, the discovery rule pauses the medical malpractice statute of limitations until the patient discovers—or reasonably should have discovered—the injury and its negligent cause, but no later than 3 years from the date of injury.
What the Law Says
California law uses a dual-trigger statute of limitations for medical malpractice claims, combining a time-based limit with a discovery-based exception.
Under California Code of Civil Procedure § 340.5, a medical malpractice lawsuit must generally be filed within one year after the plaintiff discovers—or through the exercise of reasonable diligence should have discovered—the injury and its negligent cause.
However, there is an absolute outer limit: no action may be brought more than three years after the date of injury, regardless of when the injury was discovered.
This means the clock starts either when the patient actually discovers (or should have discovered) both the harm and that it resulted from professional negligence — or, at the latest, three years after the negligent act occurred.
Statutory TextIn an action for injury or death against a health care provider based upon such person's alleged professional negligence, the time for the commencement of action shall be three years after the date of injury or one year after the plaintiff discovers, or through the use of reasonable diligence should have discovered, the injury, whichever occurs first.
— Code of Civil Procedure, § 340.5 — Actions against health care providers
What Courts Have Said
California courts have clarified how the discovery rule applies in medical malpractice cases — focusing on what a reasonably diligent patient would know, not just what they actually knew.
The court held that 'discovery' includes awareness of both the physical injury and its negligent origin — mere knowledge of symptoms is insufficient without awareness of wrongdoing.
The court reaffirmed that the discovery rule requires plaintiffs to exercise 'reasonable diligence' — the inquiry is objective, not subjective — and that suspicion of negligence triggers the duty to investigate.
What to Do
Document all symptoms, treatments, and communications with providers starting from the suspected injury date.
Consult a medical malpractice attorney as soon as you suspect negligence — do not wait to 'confirm' it.
Preserve medical records and seek an independent expert review to assess whether negligence occurred.
File your lawsuit no later than one year after you discovered (or reasonably should have discovered) both the injury and its negligent cause — and absolutely no later than three years after the injury occurred.
Sources
Not legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-06-08.