{"id":1348,"date":"2026-07-09T06:41:38","date_gmt":"2026-07-09T06:41:38","guid":{"rendered":"https:\/\/blog.franke-ip.com\/en\/?p=1348"},"modified":"2026-07-09T08:39:01","modified_gmt":"2026-07-09T08:39:01","slug":"can-relevant-prior-art-be-hidden-behind-the-closest-prior-art","status":"publish","type":"post","link":"https:\/\/blog.franke-ip.com\/en\/can-relevant-prior-art-be-hidden-behind-the-closest-prior-art\/","title":{"rendered":"Can Relevant Prior Art Be “Hidden” Behind the Closest Prior Art?"},"content":{"rendered":"
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Under EPC patent law, can more relevant \u2014 in particular, technically closer \u2014 prior art be “hidden” by instead relying on a different document with a similar purpose as the closest prior art (CPA)? The question is sharpened by the suspicion that the skilled person might somehow become “less skilled” if the more relevant document was published later and is therefore not considered as a starting point. The short answer is: No.<\/strong> Neither the chronological order of prior publications nor the choice of a document with a similar purpose can shield relevant prior art from examination. At the same time, the question does expose a genuine weak point of the approach \u2014 the imprecision inherent in the selection stage.<\/p>\n\n\n\n

1. The Skilled Person Knows the Entire State of the Art<\/h2>\n\n\n\n

The skilled person under the EPC is not a real-world searcher who finds some documents and overlooks others, but a legal fiction. This person is deemed to have had access to the entire state of the art under Art. 54(2) EPC. The publication date determines only whether<\/em> a document forms part of the prior art at all (publication before the filing or priority date) \u2014 not whether it is “findable”. Two documents published before the relevant date are equally available, regardless of which one appeared first. “Hiding” relevant prior art through later (but still pre-published) publication is therefore excluded from the outset.<\/p>\n\n\n\n

2. Selecting the Closest Prior Art<\/h2>\n\n\n\n

Under the Guidelines for Examination, G-VII, 5.1, the closest prior art is a document directed to a similar purpose or effect<\/em> \u2014 or at least belonging to the same or a closely related technical field \u2014 that requires the fewest structural and functional modifications. This purpose-based criterion is the hindsight-free criterion: the purpose of a document can be determined independently of the claimed solution. Selecting the CPA based merely on the number of features shared with the claim<\/em>, by contrast, would itself be tainted by hindsight, since it presupposes knowledge of the claim.<\/p>\n\n\n\n

3. Multiple Realistic Starting Points<\/h2>\n\n\n\n

Under settled case law (T 967\/97<\/strong>, T 21\/08<\/strong>, confirmed in T 1742\/12<\/strong>), where the skilled person has several viable routes starting from different documents, inventive step must be assessed against all of these routes. If the invention is obvious from even a single realistic route, inventive step is lacking. Two consequences follow: a document with a less similar purpose is not<\/em> discarded merely because the document with the more similar purpose failed to lead to the invention; and, conversely, a finding of non-obviousness starting from the purpose-related document does not save the invention if it is obvious from another realistic starting point.<\/p>\n\n\n\n

T 1742\/12<\/strong> frames this as a logical inversion: a document from which the invention is obvious is, by definition, the “more promising springboard” compared with one from which it is not. And T 405\/14<\/strong> makes clear that the closest prior art need not be the technically closest document: a document sharing the same purpose and many features often does not<\/em> support a convincing obviousness objection, whereas the invention may follow, without hindsight, as obvious from an apparently less promising document.<\/p>\n\n\n\n

4. Hindsight in the Selection Stage \u2014 and Where It Is Actually Controlled<\/h2>\n\n\n\n

The objection that choosing a less purpose-related CPA is itself an act of hindsight is, in part, correct. In T 855\/15<\/strong>, the Board held that the question of whether the skilled person “would” select a document in order to arrive at the claimed invention<\/em> is itself hindsight. A results-oriented selection of the springboard is therefore impermissible. That said, the mere technical distance of a document does not, on its own, exclude its use as a starting point.<\/p>\n\n\n\n

Hindsight is accordingly not controlled by prohibiting distant starting points, but at two other stages of the analysis:<\/p>\n\n\n\n