Two distinct issues produced a remand
On 26 June 2025, the Korean Supreme Court decided case 2023Hu11562, concerning a pharmaceutical composition for lowering blood pressure. It reviewed Patent Court decision 2022Heo4826 of 30 November 2023 in a proceeding to determine whether a specified invention fell within a patent’s scope. This was not a final judgment awarding damages for infringement.
The Supreme Court agreed with the rejection of a defence based on freely practicable technology, but found an error in the interpretation of the claims. It therefore set aside the judgment and remanded the case. These two conclusions must be kept separate: failure of the defence did not make the lower court’s scope analysis correct.
An excused disclosure cannot be reintroduced through this defence
The dispute involved the disclosure exception under Article 30(1) of the former Korean Patent Act. Earlier invention 1 had benefited from that exception when the patent was granted. The defence argued that the specified invention could readily be implemented by a skilled person from previously disclosed technology, independently of the patented invention.
The Court held that the same disclosure excused under Article 30(1) could not be used for that purpose, either by itself or in combination with other material. Otherwise the protection given to the qualifying disclosure would be undermined through a different route. This conclusion did not eliminate defences based on genuinely independent prior art; the remaining material did not establish such a defence in this case.
The starting point remains the wording of the claim
Claim scope is determined objectively from the language of the claims, understood in light of the description and its technical context. The description assists in identifying what the claim means; it does not justify silently broadening or narrowing the stated subject matter.
That distinction mattered because the claim named particular chemical forms and quantities. A salt, its hydrate and the active moiety are not interchangeable labels for the same dose. The substance to which a numerical amount refers must be established before the specified invention can be compared with the claim.
Which compound does each milligram amount describe?
Claim 1 required 30 mg of fimasartan potassium salt or 30 mg of its hydrate, together with 5 mg of amlodipine besylate. The Court distinguished the amount of a hydrate from the amount of potassium salt contained within that hydrate. It likewise distinguished 5 mg of amlodipine besylate from 5 mg of amlodipine as the active base.
The description separately discussed fimasartan potassium salt, its hydrate and trihydrate, and amlodipine and its besylate salt. Experimental and manufacturing examples used the trihydrate of fimasartan potassium salt and amlodipine besylate as the relevant measurement bases. Those passages supported the claim’s named chemical forms rather than replacing them with active-moiety equivalents.
The lower court’s different reading required reconsideration
The lower court had read the first quantity as 30 mg of fimasartan potassium salt or a hydrate containing that quantity of the salt, and the second as 5 mg of amlodipine. It then conducted an equivalents analysis on that basis. The Supreme Court found this interpretation inconsistent with the claim language and the description.
The error affected claim 1 and also required reconsideration of claims 4 and 12–14, which depended on it or differed in the relevant respect by medical use. The remand did not finally establish that the specified invention was outside the patent’s scope, nor did it finally determine infringement. The comparison had to begin again with the correctly construed requirements.
Review the disclosure history and the dosage basis separately
When assessing a freely practicable technology defence, first identify which disclosure actually received the statutory exception and distinguish it from independent prior art. A list of publication dates alone does not show which documents remain available for the proposed argument.
For pharmaceutical claims, align the chemical form and dosage basis across the claims, description and examples, and then compare each element with the specified composition. A salt or hydrate should not be converted into an amount of active base without support in the claim’s proper interpretation. The case illustrates why a successful answer on one defence cannot substitute for accurate claim construction.
The original figure labels and forms are preserved; the text explains the facts and the court’s reasoning.