This is a comparative study on various aspects of the Patent Act, Article 35, “Patents Granted to Unentitled Persons and Protection of Legitimate Right-Holders,”and Article 99-2, “Claim for Transfer of Patents,”both of which are aimed at protecting legitimate right-holder(s) against unentitled persons who are granted patents.

Although both articles have similar purposes, they differ in several aspects, particularly concerning the retroactive effects of recovered patent(s). Several precautions should be considered when choosing one of the remedies for protecting the legitimate right-holder(s) or recovering the patent(s).

For instance, if a patent right expires or is transferred during an action to claim the transfer of a patent, it can be highly disadvantageous to the plaintiff, possibly leading to dismissal of the claim. Therefore, filing a provisional injunction prohibiting the transfer or cancellation of patent rights, along with filing a legal action, is desirable.

Furthermore, patent rights transferred through a claim for the transfer of a patent take effect retroactively from the registration date,although not in an invalidation trial. Consequently, the scope of damages from patent infringement in an invalidation trial becomes relatively disadvantageous.

If one of the joint applicants makes an unauthorized application, the transfer of share ownership through a transfer claim is possible. However, invalidating only the shares through an invalidation trial is impossible.

On the other hand, an invalidation trial can be conducted not by the court but by the “Intellectual Property Trial and Appeal Board (IPTAB)”, with the advantage of allowing proceedings even after the expiration of rights and, providing an opportunity to correct the scope of claims after the decision has become final and conclusive.

Based on the above, considering such differences is necessary when choosing a remedy for patents to protect legitimate right-holder(s) or recover the patent(s). Furthermore, legislative consideration regarding the retroactive effect of patent rights registered under Article 35 of the Patent Act will be necessary in the future.