특허의 소급 무효와 기지급 실시료의 반환 여부 - 대법원 2014. 11. 13. 선고 2012다42666, 42673 판결을 중심으로 -

Retrospective Invalidation of Patent and Whether the Previously Received Royalties Should Be Returned as Unjust Enrichment - Focused on the Supreme Court Decision 2012Da42666, 42673 -

The Korean Supreme Court recently rendered a historic decision on the issue of whether the previously received royalties should be returned as unjust enrichment if after the license agreement, the patent was adjudged to be invalid retrospectively. In Korea, similar to Germany, U.S. and Japan, there have been strong debates among diverse legal theories, and a lower court decision had been rendered with an opinion opposite to the recent Court decision. However based on this decision by the Court, the legal practice on this issue will now be unified. In this decision, the Court denied the return of previously received royalties as unjust enrichment. In other words, the Court reasoned as follows : (1) the object of the license agreement was actually fulfilled, (2) upon a judgment of retrospective invalidation, the object of the license agreement becomes impossible to perform on a subsequent basis, and (3) therefore, the licensee is only able to cancel the license agreement prospectively. However, this decision doesn't give us sufficient grounds to explain the reason why "Negative Theory of Return Obligation" is rational and why "Affirmative Theory of Return Obligation" is irrational. In the case of transfer of technique, the patent is mainly used to specify the technique, and the technique is important and of value even if it doesn't satisfy patent requirements. So, in the case of a patent license contract transferring technique(or more specifically, technique license contract), the patent license contract will still be valid even if the patent is nullified retrospectively. In such a case, the patentee should not be required to return the royalty already paid by the licensee. However, in the case where only the patent is licensed(technique isn't transferred), the patent license contract can be nullified retrospectively in accordance with the patent's retrospective nullification, and the patent royalty already paid should be returned as unjust enrichment. I hope this Court decision will serve as a momentum for more in depth debates to be held over the issue of whether royalty already paid for patent license should be returned when the patent has been nullified retrospectively.