Defenses of Defendant

Invalidity Defense

It is well settled that in case the patented invention lacks novelty over the prior art, the patent is unenforceable. Even before the patent has been invalidated through the separate invalidity proceeding, the patent shall be regarded as being void.

As for non-obviousness challenge within an infringement lawsuit under bifurcated system, the Supreme Court has maintained their firm position for a long time that the patent is enforceable before the invalidity based on the ground of being obvious over the prior art. However, the Supreme Court changed their position through en banc decision in 2012. Therefore, a defendant raise an affirmative defense based on obviousness of the patented invention.

The Korean Supreme Court en banc decision in 2012 is that in principle, (1) an issued patent is presumed to be valid; (2) an infringement court may not decide the validity of a patent; (3) arguing invalidity of a patent in suit shall not be a defense in an infringement action; but, as detour as a practical solution, (4) in case the patent in suit is clearly to be invalid due to lack of inventive step as well as lack of novelty, it is an abuse of patent right to seek the injunction and damages based on the patent. Therefore, in order to determine such abuse of a patent right, the infringement court may examine the validity of a patent due to lack of inventive step as well as lack of novelty.

As for standard of proof, presumption of validity is not strong. The challenger can meet his burden by preponderance of evidence, not by clear and convincing. For example, obviousness arguments will be in favor of invalidity where there is inevitable combination, no synergistic effect from combination, no unexpected result.

Other Affirmative Defense

An accused infringer may assert that his practice falls in the scope of publicly known technology in which he is entitled to freely use it. Under the Korean patent law, it might be a mirror image of obviousness arguments.

Further, prosecution history estoppel, experimental use, pharmaceutical clinical test, prior user right, intervening right can be used as defense. For instance, the patent right does not extend to acts done for experimental purposes relating to the subject matter of the patented invention. Further, clinical tests for the purpose of KFDA approval of generics does not infringe a patent right. Unlike the U.S. patent law, a declaratory judgment or inequitable conduct before the PTO defense is not available.

Defendant’s Motion Practice: Deposit Cost in Advance

When a plaintiff is a foreigner having neither a residence nor a business office in Korea, a defendant can file a motion that the plaintiff has to deposit the cost of suit in advance. In this situation, a defendant is not required to respond to a plaintiff’s complaint until a plaintiff deposits the estimated cost of the lawsuit. If the foreign party does not deposit by the date the court specifies, the court may dismiss the suit. In the case where the plaintiff is a foreigner and the defendant is a Korean, the Korean defendant usually file this motion to obtain enough time for considering defense and counterclaim. The foreign party may deposit a bond.

Basics on Claims under Korean Patent Law

1. Description requirement

Article 42, paragraph 4 of the Patent Act stipulates: "claims shall be supported by the detailed description of the invention and shall define the invention clearly and concisely." Claims must be supported by the detailed description of the invention. That means that the scope of each claim must be identical or equivalent to the subject matter described in the detailed description. Thus, an applicant should draft a specification to include a wide variety of examples with respect to the claimed invention.

KIPO maintains a rather strict attitude towards the support requirement through its narrow interpretation of the scope to be supported. As a practical strategy, a divisional application rather than an amendment of claims may be used to secure the broader scope of the protection and avoid prosecution estoppel. But, because it is required that the scope of a divisional application be within the scope of the original specification, in order to secure a broad scope of protection the original specification should include sufficient examples and the descriptions of its equivalents to support the claimed subject matter.

2. Claim Interpretation

  All Elements Rule

The scope of a patent is defined by the elements of a claim. It is well settled that each element in a claim is deemed material to defining the scope of the patented invention. Therefore, only when every element defined in a claim is found in an accused product or process, the accused product or process literally infringes the patent right.

  Doctrine of Equivalents

It has been long time for the Patent Court and the Supreme Court to adopt the doctrine of equivalents as a part of Korean patent law for interpreting claims.

The rationales of the doctrine of equivalents in Korea are similar to those of the U.S. Thus, it is true that if the accused product or process performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention, the accused infringes the patent in Korea.

In particular, the Supreme Court held that the accused product or process infringes a patent where an element of the patented invention is substituted with another element and, if (i) the technical concepts or principle to solve the objective of the patented invention and the accused invention are the same or common; (ii) the substituted element in the accused invention performs substantially the same function in substantially the same way to obtain the substantially same result of the patented invention; (iii) such substitution is obvious to an ordinarily skilled person in the art. However, the doctrine of equivalents shall not be applicable to the circumstances that (iv) the accused substitution was already known to skilled persons in the art at the time of filing an application and (v) the accused element was excluded from the claimed invention during prosecution.

  Prosecution History Estoppel

Based on the doctrine of equivalents, a patentee cannot regain his rights to any elements that were abandoned through an amendment or a response during prosecution. For example, when an element is excluded through an amendment in order to secure novelty and non-obviousness in response to the examiner’s rejection, an invention with an equivalent element is outside the scope of the patent.

The Supreme Court held that prosecution history estoppel should be applied in view of specification, opinions of an examiner from filing of the application to issuance of a patent and the intent of an applicant as indicated in the amendments and arguments during prosecution. Furthermore, in a patent containing more than one claim, the prosecution history of each claim should be independently reviewed to decide whether certain subject matter was intentionally excluded from the scope of the claim.