What Must You Prove
to Win a Medical Lawsuit?

1. The legal doctrine that eases proof of causation

Recognizing that medical treatment requires specialized knowledge and that it is hard for patients to prove negligence, the Supreme Court has eased the burden of proof. The 1995 decision held that causation can be presumed if the patient's side proves that there was an act that, by ordinary common sense, could be called medical negligence, and that there was no room for any cause other than the medical treatment to intervene (for example, that the patient had no health defect that could have produced such a result) (Supreme Court Decision 93Da52402, decided February 10, 1995).

The 2023 decision refined this further. Causation is presumed if the patient's side proves that the duty of care required of an ordinary medical professional under the medical standards of the time was breached, and that this negligence probably caused the harm. However, if recognizing causation is inconsistent with medical principles or remains a vague possibility, the probability is not proven, and the party that provided the treatment can overturn the presumption by proving another cause (Supreme Court Decision 2022Da219427, decided August 31, 2023).

2. What role do expert reviews play?

• Medical record review : A specialist chosen by the court reads the records and gives an opinion on whether there was negligence and whether it is linked to the outcome.
• Physical examination : Assesses the degree of permanent disability, the rate of lost working capacity, and future treatment costs and care needs.
• Fact inquiries and document production orders : Require the hospital or related institutions to submit materials.

The expert report greatly influences the direction of the judgment. The questions put to the experts must be specific, and if the answers are inconsistent or leave something out, they must be corrected through a request for a supplementary review or additional questions.

3. How a claim for breach of the duty to explain works

The key point is that there are two kinds of claims. If you want only compensation for non-economic damages for being deprived of the right to choose, you need only show that there was no explanation at all or that it was inadequate. If, on the other hand, you want compensation for all the harm caused by an outcome such as death, you must show a substantial causal link between the inadequate explanation and the outcome, and the breach must be serious enough to be comparable to a breach of the duty of care in treatment (Decision 93Da52402).

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Written on the basis of Korean statutes in force (National Law Information Center, Ministry of Government Legislation) and court precedents as of October 20, 2026. Results may differ with amendments to the law or the facts of each case. This page is general information, not legal advice.

Written and reviewed by Attorney Dongwoo Shin — Ph.D. in Law; certified criminal law specialist and certified divorce law specialist registered with the Korean Bar Association. He handles each case personally from consultation to judgment. About the attorney →
Last updated October 20, 2026