If employees request the payment of compensation for employee’s inventions against the company, company generally takes a position of denying payment of compensation for employee’s inventions, arguing that the employee’s inventions are invalid. 
In this regard, there are some discussions on whether compensation of the employee’s inventions are exempted when there are reasons for invalidation of the employee’s inventions, or whether it is only taken into account in calculating fair compensation despite the reasons for invalidation of the employee’s inventions. However, before discussing above, it should be considered that it is necessary to review whether it is appropriate for the company to claim invalidity of employee’s invention in the lawsuit for compensation of employee’s invention.
Considering the employee‘s invention system, standing of a party in invalidation trial, estoppel of the patent assignee based on the principle of good faith, and the retroactive effect of patent invalidation, it is not reasonable to allow an employer to claim invalidity of patents in a lawsuit of employee’s invention because it causes unnecessary delay in a lawsuit for compensation of employee’s invention and it does not conform to a principle of the employee’s invention system and good faith.