Seafarers’ occupational disease under Korean law: the changes ahead
A January 2025 judgment of the Korean Supreme Court on a power distribution line worker’s thyroid cancer may have significant implications for seafarers’ compensation claims. Its treatment of reasonable inference, the possibility of combined and cumulative causes, stress and the limits of scientific research offers a possible path through longstanding difficulties in proving causation, even though the case did not concern a seafarer.
This blog post is an English translation of a Korean-language column the author contributed to the Korea Shipping Gazette on 2 June 2025. The translation is the author’s own; in the event of any discrepancy, the Korean original prevails.
The evidential barrier to recognising occupational disease
The seemingly formidable barrier of proof has begun to weaken. A judgment delivered by the Korean Supreme Court on 9 January 2025 opened a new path for assessing causation in occupational disease cases.
For a disease to be recognised as occupational under the Seafarers’ Act, two requirements must be satisfied: occurrence in the course of employment and a causal connection with employment. The former means that the disease affecting the seafarer must have arisen in the course of performing work, or ordinary activities incidental to it, under the employer’s direction and control. The latter means that there must be an adequate causal relationship between the work and the onset of the disease.
The party asserting these matters, usually the seafarer, must prove them. Accordingly, establishing the occupational connection of a disease such as cancer, with its complex latency and causes, requires a demanding sequence of enquiries: confirmation of the cancer itself, whether there was exposure to carcinogens, the association between the substance and the disease, specific findings, and the possibility of non-occupational causes. As a result, obtaining recognition of an occupational connection was not easy.
Reasonable inference where science falls short
The Supreme Court judgment did not concern an occupational disease affecting a seafarer. It concerned thyroid cancer in a worker who had worked for 20 years as a power distribution line worker.
The appellate court had declined to recognise an occupational injury or disease on the ground that there was insufficient medical evidence that the electromagnetic fields to which the worker had been exposed caused the thyroid cancer. Taking account of the purpose of the industrial accident compensation insurance system, however, the Supreme Court laid down the legal principle that, even where causation is difficult to prove clearly at the current level of scientific knowledge, it is sufficient for an adequate causal relationship between the suspected factors and the disease to be capable of proof through reasonable inference.
The combined and cumulative effects of multiple factors
In particular, the Supreme Court recognised the possibility that multiple factors might operate in combination and cumulatively. It held: “The possibility must not be overlooked that prolonged exposure to high levels of extremely low-frequency electromagnetic fields adversely affected the plaintiff’s physical condition and, in combination with other factors such as the plaintiff’s constitution or underlying disease, operated in a combined and cumulative manner to cause or aggravate the disease at issue.” In the context of ships, this means that the various harmful environments seafarers may encounter can affect them in combination.
Stress as a factor in the onset and progression of disease
The approach to stress also changed. The Supreme Court considered that excessive stress could itself trigger disease or reduce the body’s immunity and thereby adversely affect the aggravation of disease. It therefore found that the possibility could not be excluded either that work-related stress had operated as one of the causes promoting the onset or progression of the disease.
The Supreme Court acknowledges statistical limitations
Above all, a significant change was the recognition of statistical limitations. The Court took into account that research findings may be insufficient where few workers are employed in the industry concerned, or where technological advances and changes in business structures mean that former working environments are no longer maintained, because research samples are scarce and the need for research diminishes.
It also appears to have taken into account that advances in science and technology may reveal, only later, the risks of factors whose harmfulness was not recognised at the level of medical and scientific knowledge then available. Accordingly, the Court held that difficulty in clearly establishing a causal relationship between the suspected causes and the worker’s disease at the current level of medical and scientific knowledge cannot, by itself, justify denying a causal relationship between the work and the disease.
Conclusion
I expect this Supreme Court judgment to bring meaningful changes to seafarers’ accident compensation in the years ahead. In assessing causation, it will now be possible to make active use even of research findings that go no further than indicating that the harmful substance concerned may influence the onset of the disease, rather than requiring complete medical and scientific proof. In my view, cases in which recognition of an occupational disease would previously have been difficult can now hold out new hope.
Although this Supreme Court judgment did not directly determine a seafarer’s occupational disease claim, it may therefore signal a paradigm shift in seafarers’ accident compensation as well. Scientific uncertainty does not automatically mean exemption from legal liability, and a standard has also been set out that may lower the threshold for recognising an adequate causal relationship with employment.
The law has begun to look upon workers and seafarers with greater compassion. Each individual case will require careful legal examination, but I believe that at least the starting line has become fairer.
K. M. Choi is a partner at Law Offices Choi & Kim, qualified in the Republic of Korea, with over ten years in shipping disputes, marine insurance and major casualties in Korean waters. He can be reached at kmchoi@choikim.com or on LinkedIn.
This article describes Korean law and practice in general terms and is not advice on the law of any other jurisdiction. The law is stated as at the date of the original Korean publication and may since have changed, and nothing here creates a lawyer–client relationship.