Pfizer Obtains Preliminary Injunction in Korea Based on Unfinalized Patent Claims

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By Young Kim and In-Hwan Kim, Kim & Chang, Seoul; e-mail: ;


Korean courts have been reluctant to grant preliminary injunctions for patent infringement since it is generally understood that monetary compensation is an appropriate measure for patent infringement. However, the Seoul Central District Court has granted a preliminary injunction for patent infringement against CJ, a local company that manufactured and sold a generic version of Pfizer's Lyrica®. What was unique about this decision is that, for the first time in Korea, a court has granted a preliminary injunction based on corrected patent claims which have not yet been finalized through appeal. This is significant as the Korean courts have always rendered decisions based on the original patent claims in instances where the patent correction is yet to be finalized.

Korea's Unique Patent System

Similar to the practice in countries such as Germany and Japan, the patent litigation system in Korea is bifurcated. That is, a civil patent infringement action must be filed with a district court, while a patent can only be nullified in a separate invalidation action filed with the Intellectual Property Tribunal of the Korean Intellectual Property Office. However, if the district court determines that the patent is likely to be invalid, then it can refuse to enforce said patent to prevent patent abuse.

Further, upon grant, a patent may be amended or corrected by a correction action, which can be filed with the IP Tribunal at any time (even after the patent expires). However, if an invalidation action is pending before the tribunal, then the patent can only be amended by a correction petition within the framework of the invalidation action.1 In the case of a correction action, the patent will be deemed to have been granted as corrected if the tribunal renders a decision allowing the correction. However, in the case of a correction petition, the correction of the patent will only be finalized when the invalidation action decision granting the correction becomes final and conclusive.2

It has been almost always the case that accused infringers file invalidation actions before or after infringement actions are initiated. Further, patentees often amend their patent claims in response to invalidation actions. As such, it was always hotly debated whether a patent infringement action should be decided based on the original patent claims or corrected patent claims if the correction has been made in response to an invalidation action but has not been finalized. Until recently, most courts rendered decisions based on the original patent claims, not the corrected patent claims unless correction has been finalized. However, in Mitsubishi v. Intematix (Case No. 2011 Gahap 138404, February 5, 2013), the Seoul Central District Court found infringement based on the corrected patent claims when the correction has not been finalized. Specifically, the court held that although correction of the patent is still pending, the patent may be enforced against an infringer if the following conditions are met:

 (i) A correction petition has been filed; and

(ii) The patent as corrected is likely to be held valid.


The Mitsubishi case was a main infringement action seeking a permanent injunction, not a preliminary injunction action. An appeal against the district court decision was lodged and currently pending before the Seoul High Court. Further, under the Korean law, a preliminary injunction action is a separate type of civil action from the substantive action. Thus, it was still controversial whether a preliminary injunction order can be rendered against an infringer based on corrected patent claims even if the patent correction has not yet been finalized through appeal. The Seoul Central District Court addressed this issue in the present Lyrica case and concluded that a preliminary injunction order can be issued in such a situation.

Relevant Facts

Korean Patent No. 491282 (“the ’282 patent”) is directed to a new use of pregabalin3 for treating pain, which is the main indication of Lyrica®, one of Pfizer's top selling drugs.4

Even before the present infringement action was filed, many local generic companies sought to invalidate the ’282 patent before the IP Tribunal. In response to their invalidation actions, the patent was amended through a correction petition to overcome some of the invalidation grounds. While the invalidation actions were still pending before the IP Tribunal, CJ began launching its generic products. As such, a civil infringement action seeking a preliminary injunction order was filed against CJ with the Seoul Central District Court. Subsequently, the IP Tribunal rendered a decision granting the correction petition and holding the patent as corrected to be valid. Appeals against the tribunal decision were filed and are currently pending before the Patent Court. As such, correction of the ’282 patent has not been finalized.

Court Decision

In the infringement action, CJ argued that the court should decide the present infringement case based on the original claims of the ’282 patent, not the patent claims as corrected, since the correction has not been finalized through appeal. Despite this however, the Seoul Central District Court issued a preliminary injunction order based on the corrected patent claims (Case No. 2012 Kahap 515, May 20, 2013).

In reaching its decision, the court applied the following legal principles:

• Even if there are invalidation grounds for a patent, once registered, the patent should be considered to be valid unless and until an invalidation action decision holding the patent invalid becomes final. However, if the patented invention lacks novelty, then the patentee cannot assert their patent right even if there is no invalidation decision (Supreme Court en banc decision in Case No. 81 Hu 56, July 26, 1983). Further, if it is obvious that the patent will likely be invalidated in an invalidation action, then the court should not allow injunctive relief against infringement to prevent patent abuse unless there are special circumstances (Supreme Court en banc decision in Case No. 2010 Da 95390, January 19, 2012).

• A patent correction system is intended to allow a patentee to correct defects of the patent so long as the patentee does not violate the trust of a third party. That is, the patentee should be able to cure certain defects to prevent its patent from being nullified. Further, the correction of a patent, once finalized, will be effective retroactively as of the filing date of the patent (Articled 133-2(4) and 136(8) of the Patent Act). Thus, the correction system should work fully as a defensive means for the patentee.

• As such, if special circumstances exist, then a patent infringement action should not be rejected because original patent claims have invalidation grounds, even if the correction has not been finalized.


The court recognized that special circumstances exist in the present case for the following reasons:

• The correction petition made in the present case is proper since it narrows the scope of the patent claim.

• The correction is highly likely to be finalized since the IP Tribunal rendered a decision granting the correction in the invalidation actions.

• Once the correction is finalized, the ’282 patent will overcome the invalidation grounds such as lack of novelty and inventiveness and failure to meet the description requirement.

• The disputed product falls within the scope of the patent as corrected.


Further to the above, the court also independently reviewed all of the invalidation grounds asserted by CJ and rejected its invalidation defense arguments.


1 A correction petition can be filed only when the patentee submits its first response brief in an invalidation action. If there is no pending invalidation action before the IP Tribunal (even if an appeal against the tribunal decision in the invalidation action is pending with the Patent Court), then the patentee can file a correction action with the IP Tribunal.

2 The IP Tribunal decision in an invalidation action can be appealed to the Patent Court and then ultimately to the Supreme Court. It generally takes at least about 2-3 years for an invalidation action to be finally decided.

3 Pregabalin is (S)-3aminomethyl-5-methylhexanoic acid, which is known to be a derivative of a depressive neurotransmitter, GABA (gamma-aminobutyirc acid).

4 The present invention was conceived by a research team at Northwestern University and then assigned to Warner-Lambert LLC, a subsidiary of Pfizer.