In two recent decisions, the German Federal Court of Justice (Bundesgerichtshof = BGH), further developed its principles of patent claim construction. Both cases concerned the influence of the description on the scope of patent protection.

In the infringement case “Anhängerkupplung II” (judgment of 02/02/2021, case No. X ZR 170/18), a claim element was generally defined in the patent description in a rather narrow fashion. Based thereon, the appellate court had dismissed the action. The BGH, however, referred to an exemplifying embodiment not corresponding to the narrow definition and found for the plaintiff. So even if a patent description contains a general definition of a claim element, this definition may still be relativized by exemplifying embodiments. As a general rule, the principle of avoiding discrepancies between claim construction and exemplifying embodiments should prevail over definitions in a patent description (cf. BGH, judgment of 04/02/2010, case No. Xa ZR 36/08 – Gelenkanordnung).

The revocation case “Schnellwechseldorn” (judgment of 02/03/2021, case No. X ZR 17/19) related to a patent-in-suit, the description of which mentioned a certain prior art and showed that an improvement over this prior art shall be achieved with a certain claim element. The BGH held that a claim element emphasized in such manner normally cannot be understood as being present in such prior art. This may be seen as an extension of previous case-law according to which in cases, where a patent description identifies a certain prior art as corresponding to the preamble of a patent claim, the characterizing portion of said claim normally cannot be understood as covering said prior art (cf. BGH, judgment of 27/11/2018, case No. X ZR 16/17 – Scheinwerferbelüftungssystem).