More than five months have passed since the amended Trade Union and Labor Relations Adjustment Act, commonly known as the “yellow envelope law,” took effect after being revised on September 9, 2025. Since the amended act came into force, one of the most frequently raised issues has been the tension between a prime contractor’s safety and health management and the amended law: the more a prime contractor attends to the occupational safety and health of a subcontractor’s workers, the more it risks being recognized as those workers’ “employer.”
When it comes to safety and health as a working condition, facilities and equipment within a workplace account for a significant part, and in the in-house subcontracting relationships where a prime contractor’s status as an employer typically becomes an issue, such facilities and equipment are generally controlled and managed by the prime contractor alone. On this basis, the argument goes, a prime contractor that controls and manages its own facilities and equipment is effectively in a position to control and determine safety and health as a working condition as well. There is, however, room to view the matter differently, as set out below.
Under the Occupational Safety and Health Act, when workers of a related subcontractor perform work at the prime contractor’s workplace, the prime contractor bears an obligation to carry out safety and health measures to prevent industrial accidents involving both its own workers and the subcontractor’s workers. The act, however, excludes from the scope of the prime contractor’s obligations “direct measures concerning the work conduct of related subcontractor workers, such as instructions on wearing protective equipment.” The Supreme Court recently took note of this and made clear that direct measures concerning workers’ work conduct, such as instructions on wearing protective equipment, fall outside the scope of the obligation and do not belong to the prime contractor’s area of responsibility.
Lower courts have also interpreted that while a prime contractor bears safety and health obligations related to workplace facilities, it is difficult for a prime contractor to conduct direct training and measures concerning all work conduct of related subcontractor workers, and that such obligations are borne by the related subcontractor alone. Another recent ruling went further, holding that a prime contractor’s safety and health obligation lies in maintaining human and physical facilities and equipment in a state that is sufficiently safe and does not harm the health of workers performing work at its workplace, including the related subcontractor’s workers. It found that leaving the specific work methods, postures and conduct of the subcontractor’s workers, as well as the distribution of roles among them, within the subcontractor’s area of responsibility does not depart from the essence of a subcontracting agreement.
As these statutory provisions and court rulings show, safety and health management is not confined to physical elements such as facilities and equipment. Human and managerial elements are no less important: workers’ work methods and skill levels, their work postures and conduct and the training to improve them, work assignment (the division of roles), and the proper management of safety equipment and protective gear. In other words, if human and managerial elements—such as the operation of guidelines and procedures governing workers’ work conduct and methods, training and the division of roles, and the use of safety equipment and protective gear—are left within the domain of the subcontractor, there may be room to conclude that safety and health as a working condition is not necessarily controlled and determined solely by the prime contractor, which oversees the physical and environmental elements.
