Waiver of Extinctive Prescription, Epidemiological Causation and the Medical Duty to Explain: Standards of Assessment in Three Civil Damages Judgments

Question

This brief analyses three Supreme Court judgments on three questions: the limits of presuming a waiver of the benefit of prescription from partial repayment of a debt after prescription has been completed; epidemiological correlation and proof of causation in product-defect litigation; and liability for breach of approval requirements and of the duty to explain in medical treatment at the clinical-trial stage.

The first issue is the question addressed in Decision 2023Da240299: "Can a waiver of the benefit of prescription be presumed from partial repayment alone after prescription has been completed?" The second issue is the question addressed in Decision 2006Da17539: "Does product liability arise for non-specific diseases, such as diabetes, allegedly caused by exposure to Agent Orange during the Vietnam War?"

The third issue is the question addressed in Decision 2007Da3162: "How far does the duty to explain extend for a clinical-stage stem cell transplantation performed on patients with considerably advanced liver cirrhosis?" All three judgments ask how the boundaries of the statutory wording and the substantive factors for assessment are to be identified on the record.

Material to check

First (2023Da240299): the issue in this judgment is whether a debtor who acknowledged a debt after prescription had been completed can be presumed to have known of the completion and to have waived the benefit. To determine whether prescription has been completed, the records concerning "the prescription period, the starting point of extinctive prescription, and grounds for interruption or suspension of extinctive prescription" must be examined. To determine whether the debt was acknowledged, the repayment history showing "acts acknowledging the debt, such as partial repayment" and the documents recording the circumstances of the acknowledgement must be checked. To determine whether there was an intention to produce the legal effect of a waiver, objective materials showing the debtor's awareness and intention at the time of the acknowledgement must also be examined.

Second (2006Da17539): the issues in this judgment are, in product liability for Agent Orange, the defect in the product and the method of proving epidemiological causation and probability for specific and non-specific diseases. To determine the defect, the records concerning the "supply contracts with the government" and the manufacturing instructions issued by the government, together with materials showing how the product was designed and manufactured, must be examined. To determine the probability linking exposure and onset of disease, the service records showing the area of service and the timing and degree of exposure, the medical records showing the time of onset and the state of health, and the results of epidemiological studies comparing "the group exposed to the risk factor with another, general group not so exposed" must be checked. To determine the extinctive prescription issue, the registration records, applications and complaints showing the time of registration and the time at which the claimants "applied for a provisional attachment or filed suit" must be examined.

Third (2007Da3162): the issues in this judgment are whether separated cells and the mesenchymal stem cell transplantation constitute a medicinal product and a clinical trial, and whether a joint tort arises from breach of the duty to explain and the duty to inform. To determine whether there was a medicinal product and a clinical trial, the manufacturing records showing how the cells were selected, proliferated and cultured, and the approval records concerning a "clinical trial protocol", must be examined. To determine whether the duties to explain and to inform were breached, the records of press conferences, the advertisements on the hospital website and the consultation records must be checked. To distinguish a breach of the approval requirement from a breach of the duty of care, the materials verifying safety and efficacy in the light of the knowledge and experience available at the time must also be examined.

Possible readings

In Case 2023Da240299, the issue was whether a debtor who acknowledged a debt after prescription had been completed is presumed to have known that prescription had been completed and to have waived its benefit.

In Case 2006Da17539, the issues were whether, in product liability litigation, the court of the place where the damage occurred has international jurisdiction; whether, under the former Conflict of Laws Act, the place where the facts giving rise to a tort occurred includes the place where the damage resulted; and whether goods delivered directly to a specific consumer, and goods manufactured in accordance with government manufacturing instructions, are nonetheless subject to product liability and whether their makers are liable parties.

In Case 2007Da3162, the issues were whether cells separated from the human body constitute a medicinal product under the former Pharmaceutical Affairs Act; whether mesenchymal stem cell transplantation constitutes a clinical trial; whether performing a medical act constituting a clinical trial without approval is in itself sufficient to give rise to a tort; and the scope of a doctor's duty to explain in medical treatment at the clinical-trial stage.

What the decisions held

Supreme Court en banc Decision 2023Da240299 rendered 24 July 2025 held as follows: "Whether prescription has been completed is determined by various factors, such as the prescription period, the starting point of extinctive prescription, and grounds for interruption or suspension of extinctive prescription." Through this judgment, the Court holds that, even where a debtor acknowledges a debt after prescription has been completed, the debtor's awareness of the completion and intention to waive cannot be presumed forthwith. The Court stated that it is difficult to regard the debtor as having known of the completion merely because the prescription period had elapsed, and that a decision knowingly to give up a benefit is exceptional. It draws a line by holding that, because acknowledgement is an expression of awareness whereas waiver is an expression of intent to bring about an unfavourable effect, the inquiry into the intention to produce legal effect cannot be omitted. The Court relied both on the strict interpretation of waivers of rights and on the protection of debtors under Article 184(1) and (2) of the Civil Act. It requires that waiver not be concluded from partial repayment alone, and that the matter be assessed objectively by considering comprehensively the motive and circumstances of the repayment and whether it was voluntary, the difference between the amount repaid and the amount owed and the length of time that had elapsed, and the debtor's words and conduct, the relationship between the parties and the debtor's experience.

Supreme Court Decision 2006Da17539 rendered 12 July 2013 held as follows: "In the case of non-specific diseases, even if an epidemiological correlation between a particular risk factor and a non-specific disease is recognised, proof merely that an individual was exposed to the risk factor and that the individual contracted the non-specific disease cannot be regarded as proving a probability sufficient to recognise a causal relationship between the two." Through this judgment, the Supreme Court recognised the international jurisdiction of the Korean courts on the basis of a substantial connection, namely that Korea was both the place where the damage occurred and the claimants' base of life, and of foreseeability, and held that Korean law could be the governing law. Agent Orange is a product mass-manufactured and used under supply contracts with the United States government, and the defendants are manufacturers even though they produced it on the government's instructions. Where a toxic substance has no or negligible utility, repeated exposure to it poses a risk of harm, and that risk is difficult to avoid, a heightened duty to prevent danger arises, and manufacture and sale in breach of that duty involve a design defect unless there are special circumstances. The Court upheld the lower court's finding of probability linking exposure and onset for chloracne as a specific disease, but held that, for non-specific diseases such as diabetes, probability cannot be recognised on the basis of statistical association alone. The Court treated part of the extinctive prescription defence as an abuse of rights, on the grounds of the obstacles that existed until registration and the exercise of rights within a reasonable period, and did not accept proportional causation.

Supreme Court Decision 2007Da3162 rendered 14 October 2010 held as follows: "Even where a medical act constituting a clinical trial was performed without approval, in violation of the relevant statutes requiring the approval of the supervisory authority, that in itself is not a breach of the medical duty of care; therefore, unless a specific breach of the medical duty of care is established in respect of the medical act in question, that alone does not give rise to tort liability." Through this judgment, the Supreme Court, citing Article 2(4), subparagraph 2 of the former Pharmaceutical Affairs Act, held that separated cells used for treatment at the cellular level are included in medicinal products. The Court holds that the stem cells in this case constitute a medicinal product, because they were selected from umbilical cord blood leukocytes and administered after proliferation and culture outside the body. It stated that, because the safety and efficacy of the transplantation had not been verified in the light of the knowledge and experience available at the time, the transplantation constituted a clinical trial under Article 26-4(1) of the former Pharmaceutical Affairs Act, so that performing it without approval violated the Act. However, a breach of the approval requirement does not in itself directly amount to a breach of the medical duty of care; in this case, the Court recognised a joint tort arising from breach of the duties to explain and to inform, on the ground that false information about the treatment's effects had been provided.

Practical checklist

First, can a waiver of the benefit of prescription be presumed from partial repayment alone after prescription has been completed? Check separately, using the repayment history and the materials on the circumstances of the acknowledgement, whether there was an "acknowledgement of the debt by the debtor after the completion of prescription" and whether there was an intention to waive amounting to an "intention to produce legal effect".

Second, does product liability arise for non-specific diseases, such as diabetes, allegedly caused by exposure to Agent Orange during the Vietnam War? Check separately, using the medical records and the study results, whether, in epidemiological studies comparing "the group exposed to the risk factor with another, general group not so exposed", the incidence in the exposed group considerably exceeds that in the general group, and the timing and degree of exposure, the time of onset, the state of health, lifestyle habits and similar factors.

Third, how far does the duty to explain extend for a clinical-stage stem cell transplantation performed on patients with considerably advanced liver cirrhosis? Check separately, using the medical records, the explanatory documents, the advertisements and the consultation records, whether "the symptoms of the disease, the content and necessity of the treatment method, the risks expected to arise, and the like" were explained, and whether the safety and efficacy of the treatment, as one at the clinical-trial stage, were explained in comparison with ordinary, standard medical treatment.

Glossary

Standard distinguishing the completion of prescription, acknowledgement and an expression of intent to waive (2023Da240299): the Court holds that, even where a debtor acknowledges a debt after prescription has been completed, the debtor's awareness of the completion and intention to waive cannot be presumed forthwith. The Court stated that it is difficult to regard the debtor as having known of the completion merely because the prescription period had elapsed, and that a decision knowingly to give up a benefit is exceptional. It draws a line by holding that, because acknowledgement is an expression of awareness whereas waiver is an expression of intent to bring about an unfavourable effect, the inquiry into the intention to produce legal effect cannot be omitted. The Court relied both on the strict interpretation of waivers of rights and on the protection of debtors under Article 184(1) and (2) of the Civil Act. It requires that waiver not be concluded from partial repayment alone, and that the matter be assessed objectively by considering comprehensively the motive and circumstances of the repayment and whether it was voluntary, the difference between the amount repaid and the amount owed and the length of time that had elapsed, and the debtor's words and conduct, the relationship between the parties and the debtor's experience. The factors identified for assessment include "the prescription period", "the starting point of extinctive prescription" and "grounds for interruption or suspension of extinctive prescription".

Framework for assessing product defects, epidemiological causation and abuse of rights in relation to extinctive prescription (2006Da17539): the Supreme Court recognised the international jurisdiction of the Korean courts on the basis of a substantial connection, namely that Korea was both the place where the damage occurred and the claimants' base of life, and of foreseeability, and held that Korean law could be the governing law. Agent Orange is a product mass-manufactured and used under supply contracts with the United States government, and the defendants are manufacturers even though they produced it on the government's instructions. Where a toxic substance has no or negligible utility, repeated exposure to it poses a risk of harm, and that risk is difficult to avoid, a heightened duty to prevent danger arises, and manufacture and sale in breach of that duty involve a design defect unless there are special circumstances. The Court upheld the lower court's finding of probability linking exposure and onset for chloracne as a specific disease, but held that, for non-specific diseases such as diabetes, probability cannot be recognised on the basis of statistical association alone. The Court treated part of the extinctive prescription defence as an abuse of rights, on the grounds of the obstacles that existed until registration and the exercise of rights within a reasonable period, and did not accept proportional causation. The factors identified for assessment include "the timing and degree of exposure to the risk factor", "the time of onset" and "family history".

Standard distinguishing breach of the approval requirement from breach of the duty to explain in clinical-stage medical treatment (2007Da3162): the Supreme Court, citing Article 2(4), subparagraph 2 of the former Pharmaceutical Affairs Act, held that separated cells used for treatment at the cellular level are included in medicinal products. The Court holds that the stem cells in this case constitute a medicinal product, because they were selected from umbilical cord blood leukocytes and administered after proliferation and culture outside the body. It stated that, because the safety and efficacy of the transplantation had not been verified in the light of the knowledge and experience available at the time, the transplantation constituted a clinical trial under Article 26-4(1) of the former Pharmaceutical Affairs Act, so that performing it without approval violated the Act. However, a breach of the approval requirement does not in itself directly amount to a breach of the medical duty of care; in this case, the Court recognised a joint tort arising from breach of the duties to explain and to inform, on the ground that false information about the treatment's effects had been provided. The factors identified for assessment include "the symptoms of the disease", "the content and necessity of the treatment method" and "the risks expected to arise".

Sources and limitations

This brief was prepared solely on the basis of the texts of Articles 2, 166(1), 184, 750 and 766 of the Civil Act and Articles 2, 3 and 3-2 of the Product Liability Act as published on the Korea Law Information Center, and the judgments in Supreme Court Decision 2023Da240299 rendered 24 July 2025, Supreme Court Decision 2006Da17539 rendered 12 July 2013, and Supreme Court Decision 2007Da3162 rendered 14 October 2010.

This is academic research material setting out general legal principles and standards for reviewing the record; it is neither legal advice on any individual case nor an opinion for submission to a court.

Points left open

2023Da240299: if an intention to waive is not to be read into partial repayment, what more must the creditor establish?

2006Da17539: even after a statistical association has been established, what additional proof determines the probability of onset in an individual?

2007Da3162: at what point does the causation assessment, which asks whether the patients would have chosen to incur the same expenditure had there been no false information about the treatment's effects, diverge again?

When to reconsider

2023Da240299: the assessment will be revisited once the examination of the motive and circumstances of the partial repayment and whether it was voluntary, the difference between the amount repaid and the amount owed and the length of time that had elapsed, and the debtor's words and conduct, the relationship between the parties and the debtor's experience has been completed.

2006Da17539: to be examined when the incidence in the exposed group compared with the general group, individual exposure and the conditions of onset again come into question.

2007Da3162: the assessment may be revisited if new records are found of explanations of the treatment's effects in comparison with standard treatment.

Statutes referred to

• 민법 제2조, 제166조 제1항, 제184조, 제750조, 제766조
• 제조물 책임법 제2조, 제3조, 제3조의2

Decisions referred to

• 대법원 2025. 7. 24. 선고 2023다240299 전원합의체 판결 · Decision ledger
• 대법원 2013. 7. 12. 선고 2006다17539 판결 · Decision ledger
• 대법원 2010. 10. 14. 선고 2007다3162 판결 · Decision ledger

Verification status

The cited provisions (Articles 2, 166(1), 184, 750 and 766 of the Civil Act, and Articles 2, 3 and 3-2 of the Product Liability Act) and the judgments discussed (Supreme Court Decision 2023Da240299 rendered 24 July 2025, Supreme Court Decision 2006Da17539 rendered 12 July 2013, and Supreme Court Decision 2007Da3162 rendered 14 October 2010) were checked, as at 15 October 2026, against the current legislation on the Korea Law Information Center and the original texts of the Supreme Court judgments. This brief cites only the three judgments listed under the judgments discussed.