특허발명 실시계약 체결 이후 특허가 소급적으로 무효가 된 경우 부당이득반환의무

If there is a defect in the invalidity of the registered patent right, the patent right may be extinguished through the invalidation trial procedure. The Patent Act clearly stipulates that the registered patent right is deemed not to have existed from the beginning by the confirmation of the invalidation trial decision. Therefore, the legal relationship recognized on the premise that the patent right is valid must be rearranged retroactively. If a patent infringement is recognized on the premise that the patent right is valid, and civil and criminal liability are assumed on the premise, civil liability must be restored, and criminal liability must be acquitted by retrial. In this extension, if a license agreement is concluded and royalty is paid on the premise that the patent right is valid, then it is very natural to interpret that if the patent right is invalidated by the invalidation trial decision, the royalty received by the patentee should be returned as an unfair advantage. However, the Supreme Court holds that, notwithstanding the retroactive effect of invalidity of the patent, the patentee may, in principle, unless the license for the patented invention was in a state of fundamental impossibility or there is no other reason for invalidation in the license itself, request the payment of royalties during the period of validity of this period. However, this judgment not only does not conform to the general law of the return of unjust enrichment, but also justifies the holding of unjust enrichment acquired through patent rights that are not eligible for registration due to a defect in the invalidity retroactively. And there is a problem that it is against equity by treating it differently from other claims for damages or criminal liability. Moreover, Korea is characterized by relatively high rate of invalidity. If this position of precedent is accepted as it is, the incentive for patent holders to enter into a license agreement as much as possible after patent registration to obtain royalties income is bound to increase. This is because even if the patent is invalidated ex post, it denies the obligation to return unjust enrichment for royalties while restoring all other responsibilities. The duty to return unjust enrichment should be recognized, however, it would be reasonable to find specific validity by setting the scope of return differently depending on whether it was in good faith or bad intentions. I look forward to a forward-looking attitude change in the case law in the future.