A dispute over a roll-coating apparatus
On 17 November 2022, the Korean Supreme Court dismissed the appeal in case 2019Hu11268. DKT had sought to invalidate PNT’s patent for a roll-coating apparatus, filed on 21 September 2006, alleging that PNT had appropriated another party’s invention. The case concerned entitlement to obtain a patent as well as separate novelty and inventive-step objections.
Entitlement and the burden of proof
Under Articles 33(1) and 133(1)(2) of the former Korean Patent Act applicable to the case, the inventor or a lawful successor may obtain a patent; a patent obtained by someone without that right may be invalidated. The inventor is the person who actually performed the creative act underlying the technical idea. An applicant and inventor having different names does not establish an unauthorised filing: lawful succession must also be considered.
The party alleging invalidity bears the burden of proving lack of entitlement, both in the invalidation trial and in the action to revoke the resulting trial decision. That allocation determines who bears the consequence if the relevant facts remain unproven. Similar technology alone does not resolve the issue.
Independent development and the timing of access
A workshop had supplied prior invention 2 to co-patentee Mirae Nanotech before the filing. The Supreme Court accepted that the patented invention could arguably be substantially identical to that technology. But the apparatus addressed shortcomings of a master-roll system by introducing a master-sheet assembly and three sets of coating-material supply units.
Even assuming that PNT later received the prior technology from Mirae Nanotech, PNT had already independently completed a roll-coating apparatus incorporating a master-sheet assembly. Evidence was also insufficient to establish that PNT had learned the contents of prior invention 2 before filing. Delivery to a co-patentee and access by the applicant before filing are different factual propositions. The challenger’s materials did not prove unauthorised copying of prior inventions 1 or 2.
Patentability remained a separate question
The lower court also found that prior inventions 1 and 2 had not been shown to be publicly known or publicly worked in Korea before the filing date. Prior invention 3, which had been publicly known domestically, did not defeat novelty or inventive step either. The Supreme Court upheld those findings and dismissed the appeal. The domestic-disclosure analysis reflects the former law applicable to this dispute; it should not be read as a general limit on the geographical scope of prior art today.
Keep development and disclosure histories distinct
For joint development and outsourced manufacture, dated drawings, test results and revision histories should explain which technical features were completed, by whom and when. Separate records of the core configuration from later additions. A shared technical document does not, by itself, identify its inventor.
The disclosing party should retain the actual material supplied, recipients, dates and agreements governing entitlement or transfer. A challenge requires a coherent evidential link between the invention, access before filing and lack of authority. A response should establish the substance and chronology of independent development. Technical resemblance, ownership of documents and legal entitlement should each be examined on their own evidence.
The original figure labels and forms are preserved; the text explains the facts and the court’s reasoning.