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The Korean Supreme Court’s Latest Decision on the Scope of Patent Term Extensions of Pharmaceutical Drugs

In a recent decision, the Supreme Court reversed the Patent Court’s ruling that a Korean pharmaceutical company’s (“defendant”) product did not infringe a Japanese pharmaceutical company’s (“plaintiff”) granted patent whose patent term was extended [See Supreme Court 2017Da245798 Decided on Jan. 17, 2019].

Plaintiff filed a patent application in Korea and was granted a patent directed to solifenacin and a pharmaceutically-acceptable salt thereof.  Meanwhile, defendant applied and received a sale permit for fumaric acid salt of solifenacin and began to sell the same after the expiration of the plaintiff’s original patent term.  However, before the expiration of the original patent term, plaintiff’s patent had been granted a patent term extension pursuant to Article 89 (Extension of Term of Patent Right by Permit, etc.) of the Korean Patent Act, which allows a patent term extension of up to five years if the implementation of a patented invention requires a permit registration under other acts and subordinate statues that may take a long time to be issued due to safety tests, procedural protocols, etc.  As plaintiff had requested a permit to import succinate acid salt of solifenacin, plaintiff lodged a patent infringement suit against defendant with regards to its sale of fumaric acid salt of solifenacin during the patent term extension.

The issue at the Patent Court revolved around Article 95 of the Korean Patent Act, which reads “[t]he effects of a patent right, the term of which has been extended … shall not extend to any other acts except the working of the patented invention with respect to such products for which permission, etc., was the basis for registering the extension …” and the scope of the term “such products” (Emphasis added).

Plaintiff argued that the scope of the term must be interpreted based on the active ingredient involved, and therefore, the scope of the term “such products” included every salt of solifenancin.  Defendant, however, argued that the interpretation should be limited to the active ingredient evaluated at the time of grant of the permit, and thus, the scope of the term “such product” should be limited to succinate acid salt of solifenacin.  The Patent Court ruled that the scope of plaintiff’s patent whose term was extended encompassed medicines that did not require separate approval for their manufacture and imports, but as a separate approval for the sale of defendant’s product was required, the scope of plaintiff’s patent did not encompass defendant’s act.  Plaintiff therefore appealed this ruling to the Supreme Court.

The Supreme Court determined that the factors involved in deciding whether defendant’s fumaric acid salt of solifenacin is within the scope of plaintiff’s patent was dependent on whether fumaric acid salt of solifenacin can readily be selected by a skilled person in the art and whether the treatment effect and use of fumaric acid salt of solifenacin is substantially identical to the treatment effect and use of the invention of plaintiff’s patent.  The Supreme Court ruled that succinate acid salt and fumaric acid salt can readily be selected by a skilled person in the art and that the treatment effects and use of the active ingredients involved for both salts are identical.  Hence, it was determined that the scope of plaintiff’s patent encompassed defendant’s fumaric acid salt of solifenacin and the Patent Court’s ruling was reversed.

This ruling of the Supreme Court will therefore strengthen the reach of the scope of patents whose terms are extended and similar rulings have been observed overseas such as in Japan and the U.S.