T1309/24: Unusual parameters, burden of proof and insufficiency of disclosure
An analysis of decision T1309/24 on sufficiency of disclosure
In decision T1309/24, a Technical Board of Appeal of the EPO revoked European patent EP3601763 B1, relating to a cleaning system for internal combustion engines, on the ground of insufficiency of disclosure under Article 83 EPC.
The case clearly illustrates the rigorous standards applied by the EPO when the definition of the invention hinges on an unusual parameter, in this instance, a “fouling rate” of the internal combustion engine.
In short, in decision T 1309/24, the Board confirmed the principles set out in the Case Law of the Boards of Appeal, section II.C.5.5.3, which specifies that, when the invention is based on an unusual parameter devised ad hoc, the description of the patent must contain at least one explicit technical teaching that enables the person skilled in the art to determine such unusual parameter on the basis of the technical teachings contained in the patent and of the common general knowledge of the person skilled in the art.
The invention forming the subject of European patent EP3601763 B1 relates to a cleaning system for removing carbon deposits from internal combustion engines by injecting a cleaning fluid while the engine is running.
At first instance, the Opposition Division had confirmed the maintenance of the patent in amended form.
The characterizing feature of independent claim 1 of EP3601763 B1 was as follows:
- diagnostic means adapted to determine a “fouling rate”as a function of intrinsic parameters of the internal combustion engine (for example displacement, type of fuel, number of cylinders, etc.) and parameters linked to the conditions of use of the internal combustion engine (for example kilometres travelled, hours of use, percentage of kilometres travelled in town, on extra-urban roads, on motorways, etc.).
Studio Torta, as the opponent, filed an appeal before the European Patent Office, seeking total revocation of the patent for violation of Article 83 EPC, arguing that the description claimed a mere general principle without providing any concrete information for arriving at the quantification of such a “fouling rate”.
The Board identified the key issue as whether the person skilled in the art was able, on the basis of the overall technical teaching of the patent and their own common general knowledge, to determine the “fouling rate” reliably and without undue burden.
When an uncommon or unusual parameter is used to define the solution to a technical problem, the patent proprietor has the specific duty to set out all the information necessary for the person skilled in the art to be able to determine it reliably (Case Law of the Boards of Appeal, II.C.5.5.3).
On examination of the description of the patent, the Board found that the patent lists, by way of example, several parameters and introduces the notion of “weighting coefficients”, but does not disclose any mathematical formula, nor does it indicate how such parameters are to be combined, normalised, added or multiplied in order to calculate such “fouling rate”.
Consequently, a sufficiently detailed and complete description of at least one embodiment of the claimed invention is lacking.
During the appeal proceedings, the patent proprietor submitted external documentation in support of the sufficiency of disclosure, including reports of exercises conducted with university students and doctoral candidates to demonstrate the ease of devising a formula for calculating such “fouling rate”, nine years after the filing date of patent EP3601763 B1.
The Board, however, rejected the probative value of such exercises, because the students participating in the tests could not be regarded as representative of the person skilled in the art for the following reasons:
- they did not possess specific technical skills regarding the influence of the parameters on the clogging of internal combustion engines;
- they had been provided with practical data not contained in the patent, while omitting the instructions derivable from the description.
The Board therefore acknowledged that the tests conducted by the students did not in the slightest reflect the problem that the person skilled in the art would have had to address in order to verify the sufficiency of disclosure of patent EP3601763 B1, namely deriving at least one formula for determining such “fouling rate” on the basis of the overall technical teaching of the patent and their common general knowledge. The use of simulations or tests conducted by persons lacking the profile of the person skilled in the art (such as non-specialist students) therefore backfired on the patent proprietor, confirming that the invention requires research and development activity not guided by the patent.
Referring to the approach taken in decision T 63/06, the Board further highlighted the principleson the burden of proof:
- If the patent application does not provide concrete indications on the calculation of the unusual parameter, there is only a weak presumption of sufficiency;
- the opponent can overcome such presumption by plausibly demonstrating that the common general knowledge of the person skilled in the art does not allow the invention to be carried out; and
- the burden of proof of plausibly demonstrating that the common general knowledge of the person skilled in the art is in fact sufficient to achieve the claimed feature therefore lies with the patent proprietor.
The patent proprietor was unable to provide even a single formula for determining such “fouling rate” on the basis of the overall technical teaching of the patent that would work across the entire claimed scope of protection, either during the written phase of the appeal proceedings or during the concluding oral proceedings.
Consequently, the Board set aside the first-instance decision and revoked patent EP3601763 B1 in its entirety on the ground of insufficiency of disclosure.
