The Technical Board of Appeal 3.4.01 has held that under the EPC the notion of invention was not linked to “tangible” (in the sense of “material”) subject-matter. Electrical signals, the intensity of which could be measured at any time, in fact fell within the definition of “physical entity”.

With the advent of modern analog and digital technology, the question arises whether or not electrical signal forms may be patented. This question has not been answered consistently in different patent systems. Whereas the US Court of Appeals for the Federal Circuit found in its (albeit not unanimous) opinion “In re Petrus A.C.M. Nuijten” of September 20, 2007 that a specifically encoded signal was not directed to statutory subject matter and denied a subsequent petition for rehearing en banc, Technical Board of Appeal 3.5.01 of the EPO held in its early decision T 163/85 (Colour television signal/BBC) of 14 March 1989 that a color television signal characterized by technical features of the system in which it occurred did not fall within the exclusions of Article 52 (2) (d) EPC and thus was to be regarded as an invention within the meaning of Article 52 (1) EPC.

In a recent French case concerning European patent application 01934083.5, Technical Board of Appeal 3.4.01 had to reconsider the issue of signal patentability. The claimed subject-matter related to a train of defibrillation pulses separated by pauses, which resulted from dissecting the electrical discharge signal of a capacitor used for defibrillating the heart of a patient. In order to avoid physiological disadvantages of regular pulse/pause cycles cut out from an exponential discharge form, the invention provided a specific modulation of the pulse train, basically by adjusting the widths of pulses and pauses, so that an electrical parameter crucial for defibrillation followed a predetermined, physiologically more preferable function, e.g., by means of such modulation the average energy of each elementary pulse/pause cycle could nearly be kept constant over the whole exponential discharge curve.

The application had been refused by the Examining Division for lack of novelty of the then claimed subject-matter. In a separate nota bene section of its decision, the Division had added that the claimed subject-matter was also not susceptible of industrial application (Article 57 EPC) because “a train of elementary pulses as defined in claims 1 to 16 constitutes a physical phenomenon which is not sufficiently tangible for being considered as a product (or a process)” (translated from French by the author).

After having confirmed that the requirements of clarity, novelty and inventive step were met by the amended independent claims submitted at appeal proceedings, the Board eventually addressed the objection of lacking industrial applicability. In the first place, the Board observed that the term “tangible” was ambiguous in that it could more broadly relate to some measurable physical magnitude or in a more restricted way to some material body as had apparently been assumed by the Examining Division.

The requirement of a “tangible” (in the sense of “material”) character for inventions was, however, foreign to the EPC: The travaux préparatoires clearly showed that the legislators intended to retain a fairly broad definition of “invention”, thereby deliberately abstaining from the formulation of any requirements concerning the category an invention must belong to. Therefore, it could also not be assumed that any binding specification of possible categories might have been introduced by Rule 43 (2) EPC which only listed product, process, apparatus or use claims (albeit in a different context).

In this respect, the concept of invention pursuant to the EPC had to be distinguished from that of other patent systems, in particular the US system, where patent-eligible subject-matter was limited to “any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof” (35 U.S.C. § 101).

Even if account were taken of decision G 2/88 (“Friction reducing additive/MOBIL OIL III”) of the Enlarged Board of Appeal defining basically two different types of claims, i.e., “a claim to a physical entity (e.g., product, apparatus) and a claim to a physical activity (e.g., method, process, use)”, the claimed pulse train was of concrete nature insofar as it resulted from the modulation of an electrical signal (discharge of a capacitor used for defibrillation) and was susceptible to measurement at any time. Such a signal in fact fell within the definition of “physical entity” given by G 2/88.

Hence, the Board held that the nature of the claimed subject-matter was no obstacle to its patentability. Furthermore, the unequivocal possibility of realizing and using such a signal for defibrillation purposes warranted industrially applicability so that the requirements of Article 57 EPC were also met.

The decision clearly distinguishes the notion of invention pursuant to the EPC from that of other patent systems, notably the US patent system. Both systems are based on a contradistinctive approach since the EPC refrains from defining patent-eligible subject-matter, does however define subject-matter which is not patent-eligible. On the contrary, U.S.C. 35 101 prescribes an exhaustive list of statutory subject-matter (“process, machine, manufacture and composition of matter”), whereas not patentable exceptions derive from case law of the US Supreme Court (“laws of nature, physical phenomena and abstract ideas”). Holding that those four categories defined the explicit scope and reach of statutory subject-matter, and that a transitory, propagating signal as claimed by Nuijten was not a process, machine, manufacture, or composition of matter, the majority of the CAFC panel had affirmed the rejection of the signal claims in the above-cited opinion. In a dissenting opinion, Circuit Judge Linn argued that the signal claim was directed to a “new and useful manufacture” construed in a broader sense as appropriate for modern technology. This argument was however not accepted by the majority of the panel tying manufacture to “tangible articles or commodities”.

Under the EPC, the broadest definition of possible claim categories was given in G 2/88 referring to “physical entities” or “physical activities”. In T 533/09, the Board has interpreted “physical entity” to specifically include subject-matter that is concrete in that it results from the modulation of an electrical signal and is measureable at any time. In particular, such subject-matter cannot be considered to be of an abstract nature more or less characterizing the non-inventions listed in Article 52 (2) EPC.

Without citing T 163/85 (which may be considered regrettable), Board 3.4.01 arrives at, and thus confirms, the finding already given in the older decision, namely that the “T.V. signal as claimed would also not fall under this more general interpretation of the exclusions of Article 52 (2) and (3) EPC, because it is a physical reality which can directly be detected by technological means and, therefore, cannot be considered as an abstract entity, despite its transient character (…)”.

Since T 163/85 had already been followed by different Boards of Appeal in broader contexts (seee.g., T 1194/97 (“Data structure product/PHILIPS”) or T 1177/97 (“Translating natural languages/SYSTRAN”), it appears save to assume on the basis of the recent confirmation by Board 3.4.01 that signals are not generally excluded from patentability under the EPC. In particular, a transitory, propagating character is not an exclusion criterion. If a signal reflects the properties of a technical system in which it occurs by being particularly structured or formatted, and thus is adapted to, and can be detected by, technical means, it should in principle be patentable.