The case at issue in X ZR 131/09 was a utility model relating to a pharmaceutical composition containing an oxidizing agent. Claim 1 required the content of the oxidizing fall short of a certain upper threshold. According to the specification, the low content of oxidizing agent leads to an extended use-by date.
The defendant was able to prove that he had used a recipe inevitably leading to a composition falling under claim 1 but could not prove his subjective knowledge of the relation between the content of the oxidizing agent and the use-by date.
The BGH considered this sufficient. The second headnote reads (in translation):
“The subjective knowledge required for the possession of the invention exists when the activity is methodically directed to the realization of a technical teaching realizing all the features of the subject-matter of the invention (here: a certain recipe of a pharmaceutical composition). It is irrelevant whether or not the acting person has knowledge of effects being related to the realization of the subject-matter of the invention according to the specification (here: that the consideration of an upper limit for the content of oxidizing agent leads to an extended use-by date).”
In the reasons (margin number 18), the court argues that the possession of the invention can not depend on preconditions which did not become part of the technical teaching as defined in the claim. Accordingly, the knowledge of effects mentioned in the specification but not incorporated in the claim may not be decisive for the possession of the invention.
The interesting point is that adding a feature such as ".. such that the use-by date is extended" to the claim would have transformed this effect into a mandatory part of the technical teaching. According to the logic of the BGH, the failure to provide evidence proving the knowledge of this effect wozld have led to a refusal of the prior user right and - consequently - to infringement. An intersting case where the addition of a feature could theoretically enlarge the (inter partes) scope of protection.
A practical consequence exists for litigations with purported prior use-rights. Limiting the claim by adding a feature explicitly mentioning the effect of otherwise clearly defined technical features (in a co-pending nullity procedure or using the central limitation procedure of the EPO) could strongly increase the defendan's problems in providing sufficient evidence for the prior use.