When the patentee argues and proves all required elements to show infringement under each claim for injunction or damages and so on, the defendant should contend and prove contradicting facts to defeat the claim. The means of defense available to the defendant are classified into “denials,”87 for which the burden of proof lies with the plaintiff, and “defenses,” for which the burden of proof is on the defendant. The following sections focus on defenses.
The accused patent infringer denying infringement must disclose the product or process actually used. Under the amended Patent Act, the defendant denying infringement in spite of a prima facie showing by the plaintiff that the defendant is using the patented product or process must provide details regarding the product or process the defendant is actually using. If the defendant refuses to provide such details without adequate justification, the court may presume that the defendant actually committed the infringing act as claimed by the plaintiff.88
188.8.131.52 Abuse of rights
Whether the issue of inventive step of a patented invention can be examined and determined in an infringement case was subject to dispute until a Supreme Court decision in 2012. Ruling en banc in its 2010Da95390 decision on January 19, 2012, the Supreme Court expressly upheld the so-called defense of abuse of rights, forbidding the exercise of patent rights in an infringement suit when the patented invention lacks an inventive step, stating that
Even before when the administrative decision invalidating the patent is finalized, claims for damages or injunctions based on the patent may constitute an abuse of the rights and be impermissible when it is clear the patented invention lacks an inventive step and will be invalidated by the administrative invalidation proceeding. When the defense is raised that the patentee’s claim for damages or injunction constitutes an abuse of rights, the court handling the infringement suit is entitled to review and determine the inventive step issue in order to decide whether the defense is well-grounded.89
Deciding when a lack of an inventive step is “clear” may be an issue, but, in practice, the clarity requirement is considered met and is not independently examined so long as the judge finds the patented invention lacks an inventive step in the infringement suit.90
This Supreme Court decision dealt with a case where the inventive step of the patented invention was denied, but it is also considered equally applicable to cases where a patented invention lacks novelty or sufficient description so as to be invalid or is in violation of the first-to-file rule. However, the Supreme Court had held that a patented invention lacking novelty or sufficient description had no protectable scope of right even before the 2010Da95390 decision.91
The plaintiff may submit a reply of correction of the patented invention in response to the defendant’s defense of abuse of rights. It is possible to “correct” a patent to narrow the claims, correct typographical errors or clarify ambiguous language, either during an IPTAB invalidation proceeding or by filing a separate correction petition at the IPTAB, provided that the correction does not substantially alter the nature of what is claimed.
184.108.40.206 Free-to-exploit technology
The defendant may raise a defense of free-to-exploit technology to argue that the defendant’s product or process only implemented technology that was publicly known or could be easily derived from what was publicly known. The Supreme Court has held as follows:
In determining whether the technology the defendant exploits falls within the scope of rights of the patented invention, the comparison between the two is unnecessary to conclude that the exploited technology does not fall within the patented scope if the defendant’s product only consists of publicly known technologies or can be easily practiced by any person of ordinary skill in the pertinent art from publicly known technologies.92
This analysis resembles that given for inventive step but is different in that what is compared with the prior art or publicly known technology is the defendant’s infringing product, not the patented invention. In practice, the defense of free-to-exploit technology is rarely seen in infringement cases because the defendant can use the defense of abuse of rights to argue that the patented invention lacks an inventive step.93
220.127.116.11 Known technology
As discussed above, the Supreme Court has held that patent rights may not be exercised when the invention consists only of technologies that were already publicly known or in public use at the time of the filing, whether or not the IPTAB has ruled on the invalidity of the patented invention. The defendant bears the burden of contention and proof to demonstrate that the patented invention is a publicly known technology. Such a defense of known technology may be asserted in addition to the defense of free-to-exploit technology, but, in practice, it is less frequently asserted than the defenses of abuse of rights or of free-to-exploit technology.94
18.104.22.168 Patent exhaustion
Even though it is not expressly stipulated in the Patent Act, reselling or using a patented product is generally deemed acceptable and does not constitute patent infringement so long as the product is lawfully transferred from the patentee. This is called the “exhaustion doctrine” or “first sale doctrine.” A defendant may raise the defense of patent exhaustion in a patent infringement lawsuit.
The Supreme Court has acknowledged the doctrine of patent exhaustion as applicable to product inventions by ruling as follows:
When a patentee or licensee of a product patent lawfully sells the product implementing the patented invention in the territory of the Republic of Korea, the effects of the patent right shall not extend to the acts of using, assigning or leasing the product by the assignee or buyer with regard to the assigned product because the patent right on that product has achieved its purpose and is thus exhausted.95
22.214.171.124 Limited effect or lawful practice of patent right
In addition to the above defenses, the defendant may also assert defenses such as that:
- the effect of the patent is limited (Articles 96 and 181 of the Patent Act);
- the defendant has an exclusive or nonexclusive license granted by the patentee;
- the defendant has a statutory license granted under Articles 103, 104, 105, 122, 182 or 183 of the Patent Act, or
- the defendant is granted a compulsory license under Articles 98, 106, 107 and 138 of the Patent Act.96