Executive Summary
In June 2025, the European Patent Office issued landmark decision G 1/23 [1]. We reviewed the ruling in our earlier analysis, “G 1/23 – Can the EPO make a product disappear?”.
The message was clear. A product placed on the market before a European patent application’s filing date forms part of the state of the art, even if its composition or internal structure could not be reproduced without undue burden before that date.
In simple terms: if it was publicly available, it counts.
Several months on, the first Board of Appeal decisions applying G 1/23 provide clarity on two critical issues: novelty and inventive step. These decisions reshape risk analysis when considering commercially available products, trade secrets, and patent filing strategies. Below, we distil what matters, and what you should do next.
Keywords: G 1/23; state of the art; novelty; inventive step; problem-solution approach; EPO
Introduction
G 1/23 confirmed a decisive shift.
A publicly available product cannot be ignored when assessing the patentability of an invention simply because a skilled person could not analyse and reproduce it before the filing date of a patent application directed to that invention. Non-reproducibility is no longer a shield.
This matters commercially. Many businesses rely on proprietary manufacturing methods. Historically, uncertainty remained around the extent to which complex products could be cited as prior art. That uncertainty has now narrowed.
We are beginning to see how the Boards of Appeal apply this principle in practice. Two decisions, T 1044/2 [3] and T 1719/2 [1], provide practical guidance on both novelty and inventive step. Together, they define how exposed your innovation strategy may be once a product reaches the market.
T 1044/2 [3] - The First Application of G 1/23
Overview
Decision T 1044/23[3] was the first direct application of G 1/23.
The patent concerned a polyethylene composition for injection moulding. During opposition proceedings, two commercially available resins were cited against the patent. The Opposition Division initially disregarded them because their manufacturing methods were not enabled.
That reasoning pre-dated G 1/23.
Novelty
Following G 1/23, the opposition division’s decision was appealed, and the Board reversed course. The resins were commercially available before the filing date. Evidence confirmed they fell within the scope of claim 1. Under G 1/23, reproducibility was irrelevant.
The outcome was decisive: the claim lacked novelty.
Commercial implication: If a product on the market falls within your claim scope, lack of reproducibility will not save the patent.
Inventive Step
Problem-solution approach
At the EPO, inventive step is assessed using the established “problem-solution approach.”4,5 The structure is disciplined and predictable:
1. Identify the closest prior art.
2. Determine distinguishing features.
3. Assess the technical effect of those features.
4. Define the objective technical problem.
5. Ask whether the solution would have been obvious.
G 1/23 does not change this framework. It changes what may enter it.
Closest Prior Art
The Board confirmed that a commercially available product can represent the closest prior art, even if it is non-reproducible.
The reasoning was practical. If a product is on the market, it can serve as a starting point for further development. A skilled person may use it as-is or modify it.
The Board clarified two important points:
· When selecting the closest prior art, it is irrelevant whether the product’s manufacturing method is known.
· It is also irrelevant how much modification would be required to reach the claimed invention.
These issues arise later, at the obviousness stage.
The Board drew an analogy similar to the “Coca-Cola” example discussed in G 1/23. One can add lemon juice to Coca-Cola to reduce sweetness without knowing its secret recipe. The secret recipe does not prevent it from being a realistic starting point.
For businesses, this means competitors’ commercial products, however opaque, can be used for an inventive step attack.
Obviousness
Here, the distinguishing feature was polymer density. The objective technical problem was framed as: how to provide an alternative composition.
The decisive question was whether the skilled person could arrive at the claimed density without undue experimental effort.
The Board found no credible evidence that such modification could be achieved without significant experimentation, particularly given the proprietary manufacturing process and interdependence of the product’s properties resulting from changes to the process.
The attack failed.
This is the nuance. While non-reproducible products qualify as prior art, modifying complex materials, such as polymers, may still require inventive skill.
Where interdependence of a product’s properties results from changes to manufacturing processes, altering one property can destabilise others. In such cases, inventive step may survive.
T 1719/2 [1] — The ENGAGE® 8400 Polymer
Overview
Decision T 1719/21 [6] concerned a patent in the family protecting the ENGAGE® 8400 polymer, the very product central to G 1/23.
Inventive Step
Closest Prior Art
Again, the Board took a firm position: a commercially available product can serve as the closest prior art, reproducible or not.
The Board focused on realism. If the product’s properties and uses align with the patent’s objectives, it qualifies as a promising starting point.
Questions about synthesis conditions or reproducibility belong to the obviousness analysis, not to the initial selection of closest prior art.
Obviousness
The distinguishing feature was fluorine content. The technical effect was improved volume resistivity after crosslinking, relevant for solar cell encapsulation.
The Board asked a precise question: did the prior art motivate the skilled person to lower fluorine content to achieve that effect?
It did not.
Without that pointer, the invention was acknowledged as inventive. No deep analysis of synthesis conditions or reproducibility was required.
This contrasts with T 1044/2 [3] and illustrates a strategic reality: the choice of closest prior art can shape the entire outcome.
What This Means for Your Business
1. Public Disclosure Is Now a Clearer Risk
If your product is publicly available before filing, it can destroy novelty, even if competitors cannot reproduce it.
Market entry without filing is no longer a calculated gamble. It is a measurable exposure.
2. Trade Secrets and Patents Must Be Aligned Early
You can no longer rely on non-reproducibility to preserve patentability in Europe once a product is on sale.
Trade secret and patent strategies must be coordinated before launch. Delay reduces options.
3. Inventive Step Is Fact-Driven
Reproducibility no longer blocks an inventive step attack outright. However, it can still influence whether modification would have required undue effort. For complex products, such as polymers, advanced materials, and process-sensitive technologies, interdependence of the products’ properties on manufacturing processes may preserve inventive step.
Each case turns on evidence. Technical depth matters.
4. Small Differences May Still Succeed, But Rarely
The case law shows that minor distinctions from a commercial product can, in some circumstances, support patentability. But this is the exception.
The default assumption should be defensive: once a product is public, protection becomes harder.
Practical Actions
· File before launch. Align R&D and IP timelines.
· Audit commercial disclosures. Sales, samples, and marketing materials can all count.
· Stress-test claims against your own products. If it falls within your scope, so can a competitor’s.
· Document technical interdependencies. This evidence can be decisive in defending inventive step.
· Integrate patent and trade secret strategy from day one.
Final Position
G 1/23 closes a loophole. Commercial reality now drives legal analysis more directly.
Public availability means exposure. Non-reproducibility is not immunity. Inventive step remains nuanced, but evidence-led.
We operate where technical detail meets strategic protection. If your product is approaching market, or already there, the right filing and disclosure decisions must happen quietly, early, and with precision.
That is where value is protected.
References
[1] https://www.epo.org/en/boards-of-appeal/decisions/g230001ex1
[3] https://www.epo.org/en/boards-of-appeal/decisions/t231044eu1
[4] https://www.epo.org/en/legal/guidelines-epc/2025/g_vii_5.html
[5] https://www.epo.org/en/legal/guidelines-epc/2025/g_vii_5_2.html
[6] https://www.epo.org/en/boards-of-appeal/decisions/t211719eu1
By Nick Davies MPhys, PhD | Chartered and European Patent Attorney
