Medical malpractice cases in California arise when a healthcare provider fails to meet the accepted standard of medical care, causing preventable injuries or harm to a patient. Common examples include surgical errors, misdiagnosis, delayed diagnosis, medication mistakes, and negligent treatment.
However, not every medical complication or unsuccessful procedure qualifies as malpractice. To pursue a valid claim, patients generally must establish that a healthcare professional failed to provide appropriate care and that this negligence caused their injuries. A medical malpractice attorney can review your medical records, evaluate the circumstances of your treatment, and help determine whether you may be entitled to compensation.
Key Takeaways
- California’s definition is statutory, and it has four moving parts rather than one.
- An omission counts. Failing to do something is as much professional negligence as doing something badly.
- The category turns on licensure rather than job title, and reaches well beyond physicians.
- The conduct has to be within the general range of activities the provider’s licence covers.
- Conduct that falls outside the definition is still potentially actionable — under ordinary negligence rules, which are different rules.
The Definition, and Why It Is Worth Reading Slowly
The California Supreme Court has reproduced the statutory definition as covering “a negligent act or omission to act by a health care provider in the rendering of professional services,” “which act or omission is the proximate cause of a personal injury or wrongful death,” “provided that such services are within the scope of services for which the provider is licensed” and “which are not within any restriction imposed by the licensing agency or licensed hospital.”
That sentence is doing four separate jobs. Taken one at a time, each of them decides cases.
“Act or Omission to Act”
The definition puts failing to act on the same footing as acting. That is not a drafting flourish.
A large share of claims in this area concern something that did not happen — a test not ordered, a finding not followed up, a symptom not investigated, a referral not made, a deterioration not noticed. Readers who assume malpractice means a mistake made during a procedure often conclude they have nothing, when the conduct at issue is an omission the definition expressly covers.
What does not follow is that every omission qualifies. The omission still has to have been negligent, and it still has to have caused the harm. Those are separate questions. How the standard of care question gets answered in practice — by a qualified reviewer rather than by the outcome — is set out on our dental malpractice page, where the same framework applies to a single profession.
“By a Health Care Provider”
This clause is wider than most readers expect, and it is the one that most often surprises people about who can be a defendant.
The category is defined by licensure rather than by seniority or title. It is not limited to physicians, and it is not limited to the person who happened to be in the room. The Supreme Court has applied the definition to physician assistants and to supervising physicians alike, holding that a physician assistant acts within the scope of his or her licence when acting as the agent of a licensed physician.
The practical consequence is that the person whose conduct is at issue, the person who supervised them, and the institution may each sit inside the definition. Who actually bears responsibility is a separate question answered from records, but the definition itself is not the thing that narrows it.
“In the Rendering of Professional Services” — the Scope Question
Here is the clause that decides which body of law applies, and the one worth understanding before anything else.
The definition only reaches services within the scope of services for which the provider is licensed, and not services falling within a restriction imposed by the licensing agency or a licensed hospital. The Supreme Court has read that phrase as “the general range of activities encompassed by the provider’s license,” and has read the restriction proviso as requiring an actual limitation on the scope of a provider’s practice.
Why it matters: not everything that goes wrong in a medical setting is professional negligence. Harm arising from something other than the rendering of professional services is ordinarily treated as a different kind of claim — and claims inside the professional negligence category run on their own deadlines and their own limits on certain damages, which the ordinary category does not share.
So the classification is not academic. It is upstream of the filing deadline, upstream of what can be recovered, and upstream of the pre-filing steps a claim has to go through. It is also not always obvious, which is why it is a question for early assessment rather than something to settle by instinct.
“Proximate Cause of a Personal Injury or Wrongful Death”
Causation is written into the definition rather than bolted on afterwards.
That placement reflects where these claims most often fail. A patient who was already seriously unwell presents an unavoidable difficulty: the question is not whether harm occurred but whether the negligence rather than the underlying condition produced it. Establishing that is a matter of expert evidence, and it is the point at which otherwise sympathetic claims frequently stop.
The definition also names wrongful death, which matters because the people entitled to bring such a claim, and what they may recover, are governed by their own rules rather than by the rules that would have applied to the patient.
What This Does Not Tell You
Three things the definition is silent on, each of which gets asked constantly.
Whether the care was negligent. The definition says negligence is required; it does not supply the standard. That comes from what a reasonably careful provider in the same field would have done, and it is established by a qualified reviewer rather than by reading a chart yourself.
What any claim is worth. Nothing in the definition speaks to value, and the figures circulating against this search are individual outcomes from other states with other rules. California limits certain categories of damages in claims against health care providers, which is one reason outcomes from elsewhere do not transfer.
How likely a claim is to succeed. Published success rates describe populations, not cases. They are compiled from claims that reached particular stages, which is a different thing from the claim in front of you.
Talk to a California Medical Malpractice Lawyer
Value is rarely the first question in these matters. Whether what happened sits inside the professional negligence category is, because that classification governs the deadlines and the rules that follow from it.
Vaksman Khalfin, PC acts for patients and families across California, including in dental malpractice matters, with Alan D. Khalfin leading that work from the San Mateo office. The first consultation is free, and injury claims are handled on a contingency-fee basis: there is no upfront cost, attorney’s fees are owed only if we recover compensation for you, and fees and case costs are separate items set out in the written agreement. Wider material sits in the California personal injury guides.
Reviewed by Alan D. Khalfin, Partner and Managing Attorney, Vaksman Khalfin, PC (admitted in California). Last reviewed: 10/16/2026
Frequently Asked Questions
A negligent act or omission by a health care provider in the rendering of professional services, which is the proximate cause of personal injury or wrongful death, provided the services are within the scope of services the provider is licensed for and not within a restriction imposed by the licensing agency or a licensed hospital. All four parts have to be satisfied.
Both. The statutory definition covers a negligent act or omission to act. Claims about a test not ordered, a result not followed up, or a referral not made sit squarely inside the definition.
No. The category turns on licensure rather than job title. The California Supreme Court has applied the definition to physician assistants as well as to supervising physicians, holding that a physician assistant acts within the scope of his or her licence when acting as the agent of a licensed physician.
The Supreme Court has described it as the general range of activities encompassed by the provider's licence. The accompanying proviso about restrictions requires an actual limitation on the scope of that provider's practice rather than something more general.
Because the two categories run on different rules. Claims within the professional negligence category carry their own filing deadlines, their own pre-filing requirements, and statutory limits on certain damages that do not apply to ordinary negligence claims. The classification therefore shapes the claim before anything else does.
Published rankings on this question are compiled from different sources using different definitions, and most are not California-specific. What can be said is that claims about something not done — a diagnosis not reached, a finding not acted on — are well represented, which is consistent with the definition expressly covering omissions.
No meaningful average can be given, and the figures attached to this question are individual results from other jurisdictions with different damages rules. California limits certain categories of damages in claims against health care providers, so outcomes reported elsewhere do not transfer here.
Published success rates describe groups of past claims rather than any particular one, and they vary with how the underlying data was selected. What is knowable early is more useful: whether the conduct falls inside the definition, whether a qualified reviewer supports the standard of care point, and whether causation can be established.
