Patent translation errors can be difficult to spot when the translated sentence reads perfectly. Replace “median” with “average,” and the grammar may remain convincing while the calculation—and potentially the scope of protection—changes.
For companies bringing materials, medical devices, manufacturing processes, or software inventions into Korea, this is a filing risk worth examining before approval. A polished specification is not necessarily a faithful one.
The title’s warning needs one qualification: some errors can be corrected after grant, but correction is not an unrestricted opportunity to rewrite a patent. The available procedure, original disclosure, and effect on claim scope all matter. An applicant should never approve questionable terminology on the assumption that it can be repaired later.
🔬 A five-value example that changes the result
Consider a hypothetical claim requiring a measured particle-size parameter of no more than 10 micrometers. The following simplified dataset illustrates the difference between two calculations; it does not represent a client project or an actual patent dispute.
| Individual measurements | Arithmetic mean | Median |
|---|---|---|
| 2, 3, 4, 5, and 36 micrometers | 10 micrometers | 4 micrometers |
| 2, 3, 4, 5, and 86 micrometers | 20 micrometers | 4 micrometers |
The arithmetic mean is the sum divided by the number of observations. The median is the middle value after sorting.
In the second row, a limitation based on the median would satisfy the stated numerical threshold. A limitation based on the arithmetic mean would not. That comparison concerns this parameter alone, not whether a product satisfies every requirement of a patent claim.
The substitution also cannot automatically be described as a harmless narrowing. Different datasets can produce different relationships between the mean and median. Replacing one with the other may change which products meet a limitation rather than simply making the same boundary tighter.
A number can survive translation unchanged while the rule used to calculate it changes completely.
“Average” needs a definition before it needs a translation
An experienced technical reviewer will not automatically convert every occurrence of “average” into “arithmetic mean.”
Depending on the disclosure, the relevant quantity may be a weighted mean, a geometric mean, or a specifically defined material parameter. Polymer molecular-weight terminology is a familiar example: number-average and weight-average molecular weights describe different quantities. Removing the qualifier can erase a distinction central to the invention.
Particle measurements require similar care. A D50 value identifies a midpoint in a cumulative distribution, but the distribution basis matters. A volume-based D50 and a number-based D50 should not be treated as interchangeable merely because both involve a 50% point.
For Korean patent translation, the useful question is therefore more specific than “What does this word mean?”
What quantity does this application define, how is it measured, and where does that definition control the claims?
A reliable answer may require reading the test method, equations, examples, and dependent claims together. A sentence viewed in isolation may not contain enough information.
⚠️ What the 2026 guidance says about fixing the text
The European Patent Office’s 2026 Guidelines maintain a significant distinction: correcting an office decision is different from correcting documents submitted by an applicant. Errors in application or patent documents cannot be repaired indirectly by treating them as mistakes in the decision to grant. This reflects the principle associated with decision G 1/10. epo.org
The same Guidelines explain that bringing a translation into conformity with the original text remains subject to amendment requirements. After grant, the prohibition on extending the protection conferred adds a further constraint. The existence of the correct word in an original-language document does not make every proposed correction permissible. epo.org
These are European rules, not a substitute for Korean advice. Their practical relevance to an international portfolio is clear: the same translation defect may require different responses in different jurisdictions.
The PCT also addresses an important consequence of mistranslation. Under Article 46, where an incorrect translation causes a granted patent to exceed the scope of the original-language international application, the relevant national authorities may retroactively limit that scope and invalidate the excess. This is not a promise that an applicant can recover protection lost through an unduly narrow translation. wipo.int
🇰🇷 The Korean filing needs its own review
Korea provides procedures for correcting mistranslations in foreign-language international applications during permitted amendment periods. Official national-phase guidance links those corrections to procedural conditions; it does not describe an unlimited right to replace wording at any time. kipo.go.kr
For overseas applicants, the operational implication is straightforward: investigate a suspected error immediately, while Korean patent counsel assesses the available route.
Do not assume that an accepted translation, an examination request, and a granted patent offer identical correction options. Equally, do not assume that a European correction strategy can simply be transferred to the Korean application.
The translation team’s role is to establish precisely what changed. Counsel’s role is to determine the legal response. A useful issue report identifies the source passage, translated passage, relevant definition, affected claims, and technical consequence.
“This sounds more natural” is not an adequate justification for altering a statistical limitation.
Three technical situations where a fluent sentence can mislead
The following are illustrative review scenarios, not claims about completed customer engagements.
Battery materials: the distribution behind the number
A specification describes a particle distribution, while a claim refers to a particular diameter parameter. The translator retains the numerical range but replaces the defined distribution term with a general expression for average size.
The resulting wording may appear accessible while leaving the claimed parameter disconnected from the test method. Review must track the distribution basis and the measurement definition—not just the unit.
Medical-device software: a different filtering operation
A device calculates a median across successive sensor readings to reduce the influence of isolated spikes. If the translation describes averaging those readings, it may communicate a different operation.
Here, a terminology substitution can affect the description of the algorithm itself. The reviewer should compare the prose with any formula, flowchart, and worked example before approving the target text.
Industrial coatings: an example that no longer supports the wording
A coating application reports a median thickness derived from measurements at selected locations. A translated claim instead refers to mean thickness.
The experimental results may no longer demonstrate the parameter as translated. Rechecking the arithmetic can reveal the mismatch, but the translator should not silently rewrite the claim or experiment to make them agree. The discrepancy needs an explicit technical query.
🧩 Review the measurement as a connected specification
A terminology list is useful, but a list alone cannot resolve an ambiguous source. The review should connect each important parameter to its supporting information.
| Review point | What must remain intact | Warning sign |
|---|---|---|
| Statistical quantity | Mean, median, or another defined measure | Several distinct terms become one |
| Weighting basis | Number, mass, volume, or another basis | A qualifier disappears |
| Sampling | Population, locations, and number of observations | A subset becomes the whole |
| Measurement method | Instrument, preparation, and conditions | Method details are detached |
| Numerical boundary | Units, endpoints, and inequality signs | “Less than” becomes “at most” |
| Claim support | Definitions, examples, and dependencies | A claim uses an unsupported term |
This is where specialist English-to-Korean patent review adds value: it tests whether the document still describes the same technical relationship.
Automated checks can locate inconsistent terminology, missing units, or altered numbers. They cannot, by themselves, decide whether an undefined “average” should mean an arithmetic mean. A uniform translation can still be uniformly wrong.
Before approving the filing version, ask for evidence
A focused review request gives the translation team something concrete to verify:
- Identify every statistical parameter appearing in the claims.
- Locate its definition and measurement method in the description.
- Check whether the examples use the same quantity.
- Record ambiguous source wording without silently resolving it.
- Verify the approved terminology again in the final filing document.
The final check matters because a correct draft can still be affected by later amendments, copied claim sets, or formatting changes. Equations, subscripts, inequality signs, and cross-references deserve attention alongside the words.
Our Korean-language patent translation service is intended to support this close coordination between technical reviewers and filing counsel. Applicants can provide the source specification, current claims, relevant amendments, and existing terminology so that material questions are raised against the actual filing text.
Where “average” remains undefined, the appropriate deliverable is a clear question supported by the surrounding disclosure—not an invented definition. Before approval, the applicant should be able to identify exactly which calculation the translated claim requires.
Official reference points: the EPO’s 2026 Guidelines on correction and translation conformity (source: https://www.epo.org); PCT Article 46 through WIPO (source: https://www.wipo.int); Korean national-phase guidance on correcting mistranslations (source: https://www.kipo.go.kr).