Who May File Patent Invalidation Trials in Japan?

Invalidation trials in Japan Patent Office are inter parte proceedings between the petitioner and the patentee. The Patent Act allows only “an interested person” to file invalidation trials because it primarily aims to settle private disputes. At the same time, invalidation trials may contribute to the public interest because removing invalid patents would be beneficial to the public. Therefore, not only the private interest but also the public interest may be taken into account in interpreting “an interested person.” Against this background, this article analyzes and review case law by different categories. In general, “an interested person” has been broadly interpreted and it should continue to be so. This article further examined how broadly “an interested person” may be interpreted and pointed out the remaining issues.