The claimed invention and the tested compound
In decision 2024Hu10658 of 15 January 2026, the Korean Supreme Court upheld the invalidity finding for claims 1 and 3–11 of a chemical patent. The patent concerned supramolecular complexes in which valsartan, sacubitril, sodium ions and water associate through non-covalent interactions. They behave as one substance outside the body but separate into components in the body.
Claim 1 covered several solid forms but expressly excluded the crystalline 2.5-hydrate. That excluded material, with a 1:1:3:2.5 component ratio, was precisely the complex supported by the experimental examples. The specification also discussed a prodrug linking valsartan calcium salt and sacubitril, but did not identify an example within the remaining claimed complexes.
Why changing the water content was not enough
Article 42(3)(1) of the Korean Patent Act requires disclosure that enables the skilled person to understand and reproduce the invention without excessive experimentation or special additional knowledge, assessed against the relevant technical knowledge.
The specification did not adequately explain how the active ingredients formed the dual-acting complex or the non-covalent interactions in the established 2.5-hydrate. Hydration affects crystal structure. It was not shown that reducing, increasing or removing water would preserve balanced interactions and yield another reproducible complex. At the priority date, even determining whether such complexes formed, and their structure, presented substantial difficulty.
A limited holding, not a rule requiring every possible example
The Supreme Court dismissed the appeal against the Patent Court’s 30 May 2024 judgment in 2023Heo12695. Additional limitations in dependent claims 3–11 did not cure the deficiency. The holding should not be extended to claim 2, which was not included in this finding.
Nor does the decision mean that every form of every chemical invention requires its own experiment. The absence of an in-scope example mattered together with the missing explanation of complex formation and the limited predictability of other forms.
Review disclosure again after narrowing claims
When preparing or challenging a chemical patent, map each experiment to the claims: what was made, under which conditions, and which claimed forms the result actually supports. Distinguish demonstrated results from technically justified extrapolation and unresolved questions.
An amendment during prosecution or a post-grant correction may exclude the very embodiment that explains how to make the invention. A narrower claim is therefore not automatically an enabled claim. The remaining subject matter must still be reproducible from the original technical teaching.
The original figure labels and forms are preserved; the text explains the facts and the court’s reasoning.