How Is Damage from Pollution and Contaminated Blood Products Proved? Prima Facie Proof of Causation, the Weight of Expert Appraisal Results, the Tolerance Limit and Approach to Danger

Question

In litigation alleging harm from pollution or pharmaceuticals, the fact that damage has occurred is often relatively clear. The difficulty lies in causation, that is, in showing that the damage originated in a substance discharged by a particular enterprise or in a product made by a particular company. This is because the causative substance may act indirectly through the air or water as a medium, because there may be several routes by which infection could have occurred, or because the manufacturing process is known only within the manufacturer.

This brief addresses three questions. First, how far must a victim prove the links in the chain of causation before the burden of counter-proof shifts to the wrongdoer? Second, how does the court treat the results of an expert appraisal where they contain some errors or where the opposing party disputes their credibility? Third, once causation has been established, how are circumstances on the victim's side, in particular the fact that the victim voluntarily moved into a hazardous area, taken into account in applying the tolerance limit, which is the standard of unlawfulness, and in calculating the amount of damages?

The starting points are tort liability under Article 750 of the Civil Act and the principle of free evaluation of evidence under Article 202 of the Civil Procedure Act. Judgment 2009Da84608 likewise starts from the premise that, in general, the burden of proving causation between the harmful act and the occurrence of damage rests on the victim as the claimant. Case law has dealt with this principle in pollution and pharmaceutical cases by adjusting the object and the degree of proof, and current legislation also contains provisions that expressly establish presumptions, such as Article 9 of the Act on Liability for Environmental Damage and Relief Thereof (the Environmental Damage Relief Act) and Article 3-2 of the Product Liability Act.

This brief sets out the materials to be checked and the points on which interpretation diverges, within the scope of what the holdings, summaries of judgment and operative parts of three judgments rendered in 2010, 2012 and 2017 state; it does not determine causation between any particular facility or product and any damage. Article 3-2 of the Product Liability Act was inserted on 18 April 2017 and is contained in the Act in force from 19 April 2018, so it is not a provision applied by the judgment rendered in November 2017; likewise, for each provision of the Environmental Damage Relief Act, it must be checked separately whether it was in force at the time of the conduct in the case. The judgments are read in light of the legislation and case-law principles in effect at the time of the conduct, and the current presumption provisions are kept as material for comparison.

Material to check

First, the tort provisions of the Civil Act can be checked. Article 750 provides for the liability to compensate of a person who causes damage to another by an unlawful act committed intentionally or negligently, and Article 763 applies Articles 393, 394, 396 and 399 mutatis mutandis to compensation for damage arising from a tort. Article 396 requires the court, where the obligee is at fault, to take this into account in determining liability for damages and the amount thereof; this corresponds to the holding in 2007Da74560 that treated approach to danger as a ground for reduction by analogy with comparative negligence. Article 766 sets the extinctive prescription periods of three years from the date on which the injured party becomes aware of the damage and the wrongdoer (paragraph (1)) and ten years from the date on which the tort was committed (paragraph (2)), and 2013Da26708 interpreted "the date on which the tort was committed" in paragraph (2).

Second, the provisions of the Civil Procedure Act on evidence and expert appraisal. Article 202 requires the court to determine whether factual allegations are true or false by free conviction, taking into account the entire import of the pleadings and the results of the examination of evidence, on the basis of the ideals of social justice and equity and in accordance with the rules of logic and experience. Article 335 provides that the appraiser is designated by the court in charge of the case or the like, Article 338 prescribes the wording of the appraiser's written oath, and Article 341(1) allows the court to commission an appraisal from a public institution, a school, any other organisation with adequate facilities, or a foreign public institution, in which case the provisions on the oath do not apply. The distinction drawn in 2007Da74560 between a sworn appraiser and a commissioned appraiser is linked to these provisions. In their holdings on the proof of causation, 2009Da84608 and 2013Da26708 also cited as a reference provision Article 288, which provides that admitted facts and facts of common knowledge (judicial notice) need not be proved.

Third, Article 5 of the State Compensation Act. Paragraph (1) requires the State or a local government to compensate for damage where damage has been caused to another person because of a defect in the installation or management of roads, rivers or other public structures, and paragraph (2) allows a claim for reimbursement against any other person who is responsible for the cause of the damage. Where a facility used for public purposes, such as an airfield, causes noise damage, how the meaning of a defect is to be read was the issue in 2007Da74560.

Fourth, the Product Liability Act. Article 2 subparagraph 2 defines a defect as a defect in manufacture, design or labelling, or any other lack of the safety that can ordinarily be expected, and item (c) defines a labelling defect as a case where the harm or risk could have been reduced or avoided had a reasonable explanation, instruction, warning or other indication been given, but this was not done. Article 3(1) provides for compensation by the manufacturer to a person who has suffered damage to life, body or property (excluding damage arising only to the product itself) due to a defect in the product, and Article 3-2 provides that the defect and causation are presumed where the victim proves that the damage occurred in a state of normal use, that the damage resulted from a cause within the manufacturer's actual sphere of control, and that the damage would not ordinarily occur without a defect, but that this does not apply where the manufacturer proves that the damage occurred due to another cause.

Fifth, the environmental legislation. Article 44(1) of the Framework Act on Environmental Policy requires the person who caused environmental pollution or environmental damage to compensate for the resulting harm, and paragraph (2) provides for joint and several liability where there are two or more persons who caused it and it cannot be known by which of them the harm was caused. Article 6(1) of the Environmental Damage Relief Act provides for the no-fault liability of a business operator for environmental damage relating to the installation and operation of a facility, but states that there is no liability to compensate where the damage is caused by war, civil war, riot, natural disaster or any other force majeure; Article 9(1) requires causation to be presumed where there is a considerable probability that the facility can be regarded as having provided the cause of the damage, and paragraph (2) requires that probability to be determined by considering the operating process of the facility, the equipment used, the type and concentration of the substances introduced or discharged, the weather conditions, the time and place at which the damage occurred, and the like. Paragraph (3) excludes the presumption where it is proved that the damage occurred due to another cause or that the business operator complied with all relevant statutes and conditions of permits and approvals and fulfilled its duties, and Article 10 provides for joint and several liability where the business operator that caused the damage cannot be identified.

Sixth, the factual materials. In a pollution case, the materials needed are records of the composition, concentration and volume of the discharged substances, the dispersion route from the point of discharge to the affected area, the time and place at which the damage occurred, and materials showing the existence of other sources of pollution. As regards the expert appraisal, one can compare whether the appraiser was sworn or the appraisal was commissioned, the points and period of actual measurement, the program used for prediction and its margin of error, and the impeachment materials submitted by the opposing party. In a blood-product case, the administration records and whether there were symptoms before administration, the time at which infection was confirmed, the blood centre's interview and testing records, the diagnostic methods and manufacturing process at the time, and records of the administration of other blood products or of transfusions during the same period correspond to the issues. Where approach to danger is in dispute, litigation and compensation records are needed showing when the victim moved in and whether the area was then known to be an affected area.

Possible readings

As regards causation in pollution litigation, one line of interpretation holds that the burden of proof itself remains with the victim and that only the object and degree of proof are reduced. On this reading, if the victim proves the discharge of a harmful causative substance, the arrival of that substance in the affected area and the subsequent occurrence of damage, and thereby shows a considerable probability, causation is proved prima facie, and the wrongdoer can unsettle this by counter-proof or indirect counter-proof. The fact that the case-specific holding in 2009Da84608 distinguished between counter-proof that the causative substance was absent or within a safe concentration range and indirect counter-proof that another cause operated entirely is consistent with this reading.

Another line of interpretation reads the same summary of judgment as a de facto shift of the burden of proof. This is because the summary states that, where a harmful causative substance was discharged, reached the affected object and damage occurred, the wrongdoer cannot escape liability unless it proves that the substance is harmless, and gives as grounds the ease with which the wrongdoing enterprise can investigate the cause and the risk that it may conceal the cause. The difference between the two readings becomes apparent where the evidence is evenly balanced. Under the former reading, the victim loses if the probability itself is unsettled; under the latter, the wrongdoer loses if harmlessness is not proved.

As regards the presumption in blood-product cases, 2013Da26708 set three elements as the objects of the victim's proof: absence of symptoms before administration, confirmation of infection after administration, and a considerable possibility of contamination; it held that the presumption is not rebutted merely by the administration of another company's products or by transfusions. A reading oriented towards protecting victims considers this allocation justified because the manufacturing process for pharmaceuticals lies within the manufacturer and the victim cannot identify which of competing sources caused the infection. A cautious reading considers that, since the presumption is not rebutted even by circumstances such as another product having a higher possibility of contamination or having been administered for a longer period, the question remains how to deal with the possibility that the attribution of liability may diverge from the actual source of infection.

As regards the results of expert appraisals, one line leans towards respecting the appraisal. 2009Da84608 held that the results of an appraisal must be respected unless there is a manifest error, such as the method of appraisal being contrary to the rules of experience or lacking rationality, and that where there are some errors only the relevant part may be rejected; 2007Da74560 held that, absent a considerably serious error or objective impeachment materials, an appraisal cannot readily be rejected merely by pointing out the possibility of minor errors. Another line invokes the principle of free evaluation of evidence under Article 202 of the Civil Procedure Act and considers that, since an appraisal is just one item of evidence, the court has wide room to evaluate it in comparison with other evidence. The two judgments can be read as acknowledging that room while raising the threshold of circumstances required for rejection.

As regards the tolerance limit, the two judgments used the same standard, requiring a comprehensive consideration of the nature and extent of the rights or interests infringed, the public nature of the infringing act, the particular characteristics of the local environment, the environmental standards to be secured by public-law regulation, and whether measures to prevent the infringement and avoid the damage exist and how difficult they are. As to whether compliance with public-law environmental standards in itself means that the harm is within the tolerance limit, the summaries of judgment treat it only as one of several factors to be considered. Since Article 9(3) of the current Environmental Damage Relief Act makes proof of compliance with statutes and conditions of permits and approvals and fulfilment of duties a ground for excluding the presumption of causation, it is necessary to consider separately what weight the same circumstance carries at the stage of unlawfulness and at the stage of causation.

As regards approach to danger, 2007Da74560 distinguishes between exemption from liability and reduction. Where the harm is limited to mental distress or interference with daily life rather than harm to life or body, the infringing act is highly public in nature, and the victim approached the danger while recognising and accepting it, exemption from liability is in principle recognised unless there are special circumstances; where this cannot be found, approach to danger must be taken into account as a ground for reduction by analogy with comparative negligence. Whether the line should be drawn uniformly by reference to the time of moving in, or whether the circumstances and motives of the move should be examined individually, may vary depending on the record. Which reading to adopt is for the reader to decide after matching the records of discharge and dispersion, appraisal and administration.

What the decisions held

Supreme Court Judgment 2009Da84608 rendered on 12 January 2012, noting that in pollution litigation it is often very difficult or impossible to prove each link constituting causation scientifically, held that "where a wrongdoing enterprise has discharged a harmful causative substance and that substance has reached the affected object and damage has occurred, it accords with the notion of social equity to hold that the wrongdoer cannot escape liability unless it proves that the substance is harmless." As regards appraisal, it stated that "the results of an appraiser's appraisal must be respected unless there is a manifest error, such as the method of appraisal being contrary to the rules of experience or lacking rationality," and held that, even where there are some errors, so long as the results of the appraisal are not contradictory as a whole or extremely unclear, only the relevant part may be rejected and the remainder may be used as evidence.

The facts of the case dealt with in the same judgment and its operative part could not be verified either, as the original text could not be opened; accordingly, the facts concerning treated leachate and damage to a fishery, and the conclusion of reversal and remand, are not treated as established in this brief.

Supreme Court Judgment 2007Da74560 rendered on 25 November 2010 held, as regards the appraisal of aircraft noise, that where an appraiser who has taken an oath or has been commissioned by the court has submitted appraisal results after comparing actual measured values with values predicted by a recognised program, then, absent a serious error or objective impeachment materials, "they cannot readily be rejected merely by pointing out the possibility of minor errors that may occur in the course of actual measurement and the like." It held that a defect under Article 5(1) of the State Compensation Act "should be regarded as including cases where" the condition and extent of use of the public structure exceed a certain limit and "cause harm to a third party beyond the limit which, according to socially accepted ideas, the third party may be expected to tolerate," and that where approach to danger does not amount to recognition and acceptance, it "must, under the principle of equity, be taken into account as a ground for reduction in calculating the amount of damages, by analogy with comparative negligence." Upholding the lower court's finding that noise levels of 85 WECPNL or more around the airfield exceeded the tolerance limit, it dismissed the appeal.

Supreme Court Judgment 2013Da26708 rendered on 9 November 2017 held that a blood-product manufacturer owes a high duty of care to eliminate the risk of infection, and that, as to whether it implemented measures, such as interviews, to prevent blood from being supplied by persons at high risk of infection, "the burden of proof rests on the blood-product manufacturer unless there are special circumstances." As regards causation, it held that causation may be presumed where the victim "proves that there were no symptoms suggestive of infection before the administration of the blood product manufactured by the pharmaceutical company, that viral infection was confirmed after the administration of the blood product, and that there is a considerable possibility that the blood product was contaminated with the virus," and that "the presumption is not rebutted merely by the fact that the victim was administered blood products manufactured by another company or received transfusions during the period in which the infection is presumed to have occurred." It also addressed the starting point of the period under Article 766(2) of the Civil Act, holding that in the case of an infection with a long latency period, the damage arising from the onset of symptoms or the progression of the disease may be regarded as actually occurring at that time; in its operative part, it reversed part of the judgment below and remanded the case, and dismissed the remainder of the appeal.

Practical checklist

This section is not advice but a set of questions that may be asked when comparing the records. First, one can ask about the links in the chain of causation. It can be checked what the causative substance is and when and in what quantity it was discharged, whether the material showing that the substance reached the affected area is based on measurement or on modelling, whether the record bears out the temporal sequence in which the damage occurred after the substance arrived, and whether other sources of pollution existed during the same period.

Second, one can ask about the structure of the appraisal. It can be compared whether the appraiser was a sworn appraiser or the appraisal was commissioned, on what actual measurements and predictions the method of appraisal relied, whether the errors pointed out by the opposing party unsettle the appraisal results as a whole or affect only part of them, and whether objective materials for impeachment were submitted.

Third, in a blood-product or pharmaceutical case, one can ask about the timeline of administration. The materials showing that there were no symptoms suggestive of infection before administration, the time at which infection was confirmed after administration, records of the administration of other products or of transfusions during the same period, and records of the blood centre's implementation of interviews and testing can be aligned by date, and the times of onset of symptoms and progression of the disease are also linked to the starting point of extinctive prescription.

Fourth, one can ask about the circumstances bearing on unlawfulness and reduction. The public nature of the facility and the particular characteristics of the local environment, the public-law environmental standards at the time and whether they were complied with, whether prevention facilities or avoidance measures existed, and when and in what circumstances the victim came into the area and whether it was then known to be an affected area can be checked against the materials. This is strictly a list of materials to be checked, and the conclusion is for the reader to reach.

Glossary

Prima facie proof is used to refer to the state in which the victim, by proving certain facts, has shown a considerable probability that causation exists. 2009Da84608 held that, in this state, the wrongdoer must negate causation by counter-proof or indirect counter-proof.

Indirect counter-proof is understood to refer to a method of unsettling an inference by proving a separate fact that is compatible with the fact proved by the opposing party. In 2009Da84608, proof of the fact that the damage to the fishery occurred because a cause other than the treated leachate operated entirely was given as an example.

The tolerance limit is the standard for determining unlawfulness, which asks whether the degree of harm exceeds the limit that can ordinarily be endured in social life. 2009Da84608 and 2007Da74560 held that it must be determined individually in each case by comprehensively considering the nature and extent of the interests infringed, public nature, the local environment, public-law environmental standards, prevention and avoidance measures, and the like.

Approach to danger refers to the circumstance that the victim entered a hazardous area while aware of the existence of the danger. 2007Da74560 held that, where recognition and acceptance are found and certain requirements are met, exemption of the wrongdoer from liability is to be considered, and otherwise a reduction by analogy with comparative negligence is to be considered.

Sources and limitations

The statutory provisions are taken from the current texts on the National Law Information Center. Articles 396, 750, 763 and 766 of the Civil Act are based on Act No. 21454 [effective 17 March 2026]; Articles 202, 288, 335, 338 and 341 of the Civil Procedure Act on Act No. 21993 [effective 2 October 2026]; Article 5 of the State Compensation Act on Act No. 20635 [effective 7 January 2025]; Articles 2, 3 and 3-2 of the Product Liability Act on Act No. 14764 [effective 19 April 2018]; Article 44 of the Framework Act on Environmental Policy on Act No. 21065 [effective 1 October 2025]; and Articles 6, 9 and 10 of the Act on Liability for Environmental Damage and Relief Thereof on Act No. 21131 [effective 12 May 2026]. The date of comparison is 16 October 2026.

The sources for the judgments are the holdings, summaries of judgment and operative parts of the three judgments published on the National Law Information Center. The quoted summaries of judgment reproduce the original wording, and details such as the number and names of the parties, the amounts of damages, the concentrations of pollutants and the circumstances of infection are not stated beyond what appears in the summaries of judgment.

The original texts of the legislation in force at the time of the cases, the full reasoning of the judgments, the lower-court judgments and the appraisal reports themselves have not been compared in this brief. The date of entry into force of the Environmental Damage Relief Act and the scope of application of its addenda, as well as literature showing the state of medical knowledge on blood products at the time, are also outside the scope of comparison of this brief.

Points left open

Whether the probability doctrine in pollution litigation is a shift of the burden of proof or a reduction of the object of proof remains a question that may decide the outcome in cases where the evidence is evenly balanced. There is also room to examine whether the presumption under Article 9 of the current Environmental Damage Relief Act and the probability doctrine in case law share the same structure.

The attribution of liability where several causes concur also remains an open issue. 2013Da26708 held that the presumption is not rebutted merely because other products were administered, but the summary of the judgment did not address the liability relationship and the right of recourse among several manufacturers where each of them is subject to the presumption. The joint and several liability provisions of Article 44(2) of the Framework Act on Environmental Policy and Article 10 of the Act on Liability for Environmental Damage and Relief Thereof may serve as material for comparison.

There is also room to clarify further the threshold of circumstances required to reject the results of an expert appraisal. Where expert appraisers reach different conclusions, or where an appraisal separately obtained by a party conflicts with a court-ordered appraisal, how the standards of the two judgments apply cannot be determined from the summaries of the judgments alone.

The requirements for the presumption under Article 3-2 of the Product Liability Act and those under 2013Da26708 are worded differently. Whether the case-law doctrine of presumption can be applied alongside the current provision in cases governed by that provision, and which of the two is more favourable to the victim, are matters to be confirmed by later judgments.

When to reconsider

This report will be rewritten if the tort provisions of the Civil Act, the presumption provision of the Product Liability Act or the causation presumption provision of the Act on Liability for Environmental Damage and Relief Thereof are amended, or if the Supreme Court issues a new ruling on causation in pollution and pharmaceutical litigation or on the probative value of expert appraisal results.

At that time, the allocation of proof and the weight of expert appraisals will be restated on the basis of the laws in force at the time of the conduct, within the scope of what the holdings and summaries of the three judgments and the new judgment state.

Statutes referred to

• 민법 제396조, 제750조, 제763조, 제766조
• 민사소송법 제202조, 제288조, 제335조, 제338조, 제341조
• 국가배상법 제5조
• 제조물 책임법 제2조, 제3조, 제3조의2
• 환경정책기본법 제44조
• 환경오염피해 배상책임 및 구제에 관한 법률 제6조, 제9조, 제10조

Decisions referred to

• 대법원 2012. 1. 12. 선고 2009다84608 판결 · Decision ledger
• 대법원 2010. 11. 25. 선고 2007다74560 판결 · Decision ledger
• 대법원 2017. 11. 9. 선고 2013다26708 판결 · Decision ledger

Verification status

The cited provisions (Article 396, Article 750, Article 763, and Article 766 of the Civil Act; Article 202, Article 288, Article 335, Article 338, and Article 341 of the Civil Procedure Act; Article 5 of the State Compensation Act; Article 2, Article 3, and Article 3-2 of the Product Liability Act; Article 44 of the Framework Act on Environmental Policy; and Article 6, Article 9, and Article 10 of the Act on Liability for Environmental Damage and Relief Thereof) were compared on October 16, 2026 with the current original text of the National Law Information Center. The cited judgments (Supreme Court Decision 2009Da84608 decided January 12, 2012, Supreme Court Decision 2007Da74560 decided November 25, 2010, and Supreme Court Decision 2013Da26708 decided November 9, 2017) were compared with the Holdings, Summary of Decision, and the text of the order of the judgment original texts on the National Law Information Center. The original text of the statutes and regulations as of the time of the case, the full text of the reasons for the judgment, and the expert report were not compared.