In civil litigation, the plaintiff bears the burden of proof of holding the defendant liable for damages. However, in modern cases such as medical malpractice, pollution, and product liability, it is difficult for the plaintiff to bear the burden of proof throughout the entire process of causation because of the ubiquity of evidence and the high level of expertise required for proof. To overcome this situation, a growing trend seeks to ease the plaintiff’s burden of proof by creating a presumption of primary facts when the plaintiff proves indirect facts.

Even in civil litigation for trade secret infringement, plaintiffs have difficulty in proving the defendant’s trade secret infringement because of the ubiquity of trade secret related evidence. According to the “Survey on Technology Protection of Trade Secrets of Enterprises” conducted in 2022, approximately 61% of the participants cited “difficulty in collecting evidence of damage caused by the leakage of trade secrets” as the greatest obstacle. This article analyzes the cases of China and Japan to examine whether it is reasonable and necessary to introduce a presumption rule in trade secret infringement lawsuits and derive appropriate legislative directions for the Korean legal system.