Article 163 of the Korean Patent Act regulates the rule of res judicata, which prohibits the re-trial of a final and conclusive decision over the same facts and evidence by any party. The doctrine of res judicata prevents parties from filing identical petitions that abuse the patent trial process and promotes judicial economy of trial proceedings while preventing parties from having to respond to the same issues repeatedly. The doctrine is also applied to preserve the credibility of prior trial decisions and consistency by eliminating the possibility of contradictory decisions.
Previously, the Korean Supreme Court held that res judicata should be applied at the time of rendering the trial decision. The problem with this interpretation was that if several invalidation petitions are filed against the same patent based on the same facts and evidence, then depending on whose action becomes conclusive first, the other party's actions are deemed retroactively unlawful even if such actions were pursued to claim legitimate legal interest. For example, even if the Supreme Court rules that a patent is invalid due to obviousness, this decision is ultimately moot in accordance with the rule of res judicata if there is a different conclusive decision finding that the patent is not obvious.
As a result, in an en banc ruling, the Supreme Court recognized that applying res judicata at the time of rendering a decision may violate the individual's constitutional right to a trial and lead to injustice since court decisions would be rendered meaningless. Therefore, the Supreme Court held that res judicata should be applied at filing of a petition for a trial.
This decision is significant as it guarantees an individual's right to a trial by changing the court's standard for determining when to apply res judicata.