# Inventive step without hindsight: the curved-cover protective-film decision Korea’s Supreme Court explains the filing-date perspective and distinguishes inventive step from sufficient disclosure in corrected patent claims. Source: https://www.iplexlaw.co.kr/en/blog/brunch-case-1800 HOME / NEWS & INSIGHTS NEWS & INSIGHTS Inventive step without hindsight: the curved-cover protective-film decision Korea’s Supreme Court explains the filing-date perspective and distinguishes inventive step from sufficient disclosure in corrected patent claims. Patents 2026.10.06 published IPLEX 6 min read Which invention was before the court? On 25 September 2025, Korea’s Supreme Court dismissed the appeal in 2025Hu10169, an invalidation dispute concerning a curved-cover protective film, its attachment apparatus and method. The tribunal had rejected the invalidation challenge; the Patent Court then dismissed the action in 2021Heo4638 on 13 February 2025. The invention under review was the corrected invention following correction decision 2023Jeong(cancellation judgment)2. A comparison based on the original claims would therefore miss the actual subject matter. Claims define the technical features for which protection is sought; the operative corrected wording must come first. Reconstruct the technical position at filing The Court required the scope and content of the prior art, differences from the claimed invention and the ordinary skilled person’s technical level to be established from the evidence. The question is then whether, at filing, that person could readily overcome the differences and arrive at the invention. Neither a difference alone nor the prior existence of individual components settles inventive step. Reading the patent first and using its solution to reorganise earlier materials is hindsight. In a hypothetical combination of device A and component B, their separate existence is only the beginning: the evidence must explain why the particular combination was readily available at the relevant time. This illustration does not describe the actual claim. The corrected claims and the outcome The Patent Court identified differences between corrected claim 1 and prior inventions 6 and 1. It found that combinations 6/8 and 1/4/5/8 did not enable the skilled person readily to overcome those differences. Inventive step was therefore not negated for claim 1 or dependent claims 3, 4, 5 and 7, which incorporated it directly or indirectly. The Supreme Court noted some shortcomings in the lower court’s explanation but accepted its conclusion, finding no outcome-affecting error in claim interpretation or inventive-step analysis. That is not an endorsement of every sentence below. Nor does an invalidation judgment establish inventive step for an entire product category or prove that every similar product infringes. Inventing easily and carrying out easily are different tests Article 42(3)(1) of the Korean Patent Act concerns a description sufficiently clear and detailed for the skilled person readily to carry out the invention. The Patent Court found this requirement satisfied, and the Supreme Court identified no material error in that conclusion. Inventive step asks whether the invention was readily derivable from the pre-existing art. Sufficient disclosure asks whether the reader, now given the specification, can implement it. Ease of implementation after reading the solution does not establish that the solution was obvious before it was disclosed. Preparing a useful validity analysis Begin with the corrected independent claim and map each dependent claim to its parent. For an invalidity challenge, explain which reference supplies which feature and why the remaining differences were readily overcome at filing; the number of references alone is not persuasive. For the proprietor, explain the technical difficulty rather than merely asserting difference. Keep the inventive-step case separate from the disclosure case, with evidence suited to each. At drafting, connect the technical problem, concrete configuration and operation. The decision reinforces a disciplined sequence: identify the claim, establish the prior art, examine the differences at the correct date, and independently assess whether the specification teaches implementation. The original figure labels and forms are preserved; the text explains the facts and the court’s reasoning. Read the Korean source This article reflects the information available when it was published. Contact us to discuss your circumstances. Discuss this topic ↗ All articles Related service: Patents & utility models ↗ Related service: IP disputes & appeals ↗ ON THIS PAGE Which invention was before the court? Reconstruct the technical position at filing The corrected claims and the outcome Inventing easily and carrying out easily are different tests Preparing a useful validity analysis TALK TO IPLEX Discuss your IP questions We consider your technology and business needs together. ↗ Contact us Newer Baidu’s RAG approach to conflicts between model answers and retrieved knowledge ↗ Older Inconsistent design drawings: when does a Korean registration survive? ↗ Related insights Patents 2026.10.16 Alloy patents: why different numerical ranges may not establish inventive step Korean Supreme Court case 2023Hu10637 examines composition, intended use and evidence of technical effects in welding-wire claims. ↗ Read article Patents 2026.10.15 Who must prove that a patent was filed without entitlement? 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