Functional Features – Essential Features: A New Perspective under Article 84 EPC

A recently published decision of the Technical Boards of Appeal of the European Patent Office (T 0809/12) concerns a case where a functional technical feature of the claim is defined as a result to be achieved.

Functional features defining a technical result are generally permissible in a claim if (i) such features could not otherwise be defined more precisely, (ii) such features were sufficiently clear for the expert to reduce them to practice without undue burden, and (iii) the state of the art does not stand in the way of using such general and broad terminology (Case Law of the Boards of Appeal, 7th ed., II. A. 3.4).

The Board distinguished between two different cases:

• (a) the functional feature defined as a result to be achieved corresponds essentially to the problem underlying the application, and
• (b) the functional feature defined as a result to be achieved does not correspond essentially to the problem underlying the application.

The present case concerned a heat treatable coated article with an IR infrared reflecting layer. According to the patent application, there exists a need in the art for a low-emissivity low-E coating or layer system which after heat treatment substantially matches in color and/or reflection (as viewed by a naked human eye from the glass side) its non-heat treated counterpart. Therefore, the relevant claim of the patent application contained the functional feature “said coated article has a ΔE* value (glass side) no greater than 2.5 after or due to heat treatment”, i.e. this feature is not only defined as a result to be achieved but also corresponds essentially to the problem underlying the application (case (a) above).

The Board concluded that, if an independent claim contains a feature defined by a result to be achieved which essentially corresponds to the problem underlying the application, to comply with Article 84 EPC the remaining features of the claim must comprise all essential features necessary for achieving that result (Reasons No. 2. 8). All those (structural or functional) features are regarded to be essential which are necessary to solve the technical problem, i.e. which are necessary to obtain the desired effect.

As a conclusion follows to sum up that an independent patent claim must contain all essential (structural or functional) features necessary to obtain the desired effect for solving the technical problem in view of the closest prior art.