1. The right of prior use protects a vested right that arose before the filing date or the priority date of a patent in relation to the patent owner. Dogmatically, the right of prior use is to be categorised as a “right of continued use”, which the prior user can assert against the exclusive right of the patent owner.
It is difficult to assess the scope of a right of prior use once it has arisen. There is no doubt that the prior user can exercise his vested rights in the same way as he used or prepared them on the filing or priority date of the patent. However, cases in which the prior-use product or process is further developed over time, which generally follows economic needs, are problematic.
In recent years, the Federal Court of Justice has repeatedly commented on the scope of the right of prior use and on deviations from the originally used embodiment. In its recent decision “Faserstoffbahn” of 20.06.2023 (file no. X ZR 61/21), the BGH specifies its case law and addresses the question of the extent to which a right of prior use can include the use of the subject matter of sub-claims.
2. Pursuant to Section 12 (1) sentence 1 PatG (German Patent Act), the patent does not take effect against the person who has already put the invention into use in Germany on the filing or priority date or has in any case taken the necessary steps to do so. For utility models, this provision applies via the reference provision of Section 13 (3) GebrMG. In proceedings before the UPC, Art. 28 UPCA stipulates the validity of Sec. 12 PatG for German parts of European patents and for unitary patents in relation to the territory of Germany.
Pursuant to Section 12 (1) sentence 2 PatG, the prior user is authorised to exploit the invention for the needs of his own business in his own or third-party manufacture site. The statutory provision does not contain any further details on the material scope of an effectively created right of prior use. The scope of the right of prior use is therefore handled rather restrictively by the courts of lower instances to the detriment of the defendant.
3. The general principle is that the prior user is generally limited to the use for which all requirements were met prior to the filing or priority date. Further developments beyond the scope of the previous use are not permitted if they interfere with the subject matter of the protected invention.
Therefore, the BGH considers the limits of the right of prior use to be exceeded if all features of a patent claim are realised for the first time in the attacked embodiment, whereas this was not yet the case in the previously used embodiment due to the absence of one of these features (BGH GRUR 2002, 231, 234 – Biegevorrichtung). Such a further development interferes with the subject matter of the invention protected by the patent, whereby it is irrelevant whether the newly used feature was obvious or evident (BGH GRUR loc. cit., p. 233).
Patent owners took advantage of this case law by combining main claims with one or more sub-claims to create an object which the defendant had not yet used before, even if he could oppose the main claim with his right of prior use. This approach was usually successful with the argument that the features of the sub-claim were realised for the first time and thus the further development interfered with this protected subject matter.
4. In the decision “Faserstoffbahn”, the Federal Court of Justice deals with the combination of sub-claims in the requests for action in infringement proceedings – here in the context of a utility model dispute.
Referring to its decision “Schutzverkleidung” (GRUR 2018, 816), the BGH first summarises recent case law. The subject matter of the scope of protection may be impaired if the prior user utilises the inventions to a greater extent than corresponds to its vested rights or if he uses the invention in a different way than was the case before the filing or priority date. However, the right of prior use must not be so narrowly defined that the prior user cannot make any commercially reasonable use of it, which includes adaptation and further development due to economic needs. This is because there are often many years between the filing or priority date and an infringement action.
Whether there is a different form of use than that protected by prior use is to be decided on the basis of the claims taking into account the description and drawing. Changes that have no influence on whether and in what way the technical teaching is realised are irrelevant for the right of prior use. However, if at least one feature of the claim is involved in a technically different way than was the case before the filing or priority date, this may exceed the limits of the right of prior use.
However, in this case too, a decision must be made as part of an overall assessment. An appropriate balance must be found between the interest of the prior user in being able to use the acquired right to sue in an economically viable manner and the interest of the patent owner in only having to tolerate the use of his patent insofar as the protected technical teaching has been recognised and implemented by the prior user. The limits of the right of prior use could be exceeded if an additional advantage is realised with the modification.
This is particularly the case if an object is used for the first time which is emphasised in a sub-claim or in the description because of this additional advantage. If, on the other hand, two completely equivalent alternatives are mentioned for a feature of a claim, the fact that the previous user only used one of these alternatives at the filing or priority date will not normally justify a corresponding restriction of his right to use. The same applies if the patent specification discloses a deviation from the prior use which is a obvious modification which, from the point of view of a person skilled in the art, can be taken into consideration without further ado with the prior user’s possession of the invention.
5. In the “Faserstoffbahn” decision, the Federal Court of Justice now extends the right of prior use to include the modification of prior-use subject-matter if this subject-matter fulfils all the features of an independent claim, but nevertheless does not have other features included in the application.
In the case to be decided, limited claims for protection of the utility model were asserted by including features from sub-claims or from the specification. Specifically, the case concerned absorbent fibre webs which are used in panty liners, among other things. In a parallel cancellation procedure, the main claim was limited by including two sub-claims, according to which the fibrous webs had an addition of substances, this addition comprising a superabsorbent polymer. It was undisputed that the previously used product did not contain any superabsorbent polymers.
The Court of Appeal rejected a right of prior use. In the opinion of the BGH, however, it was necessary to examine whether the modification realised an additional advantage or whether it was a completely equivalent alternative or an evident modification. Contrary to the opinion of the Court of Appeal, this is also of importance if the additional features of the sub-claim are realised for the first time with the modification. Emphasising a feature of a sub-claim may in individual cases indicate that it is a relevant additional advantage, i.e. an advantage according to the invention. However, the mere inclusion in a sub-claim cannot replace the substantive examination of whether such an advantage exists or whether it is merely a completely equivalent alternative or an evident modification. However, as in the “Schutzverkleidung” decision, the BGH leaves open whether the scope of the right of prior use includes not only evident modifications, but also those modifications that were obvious to the skilled person with the prior user’s possession of the invention.
The BGH makes it clear that the substantive scope of a right of prior use is not to be assessed schematically according to whether additional features from a sub-claim or from the description are realised for the first time in a further development. It must always be examined whether this is the first time that an additional advantage of the patent has been realised which was not evident to a person skilled in the art. The BGH referred the case back to the court of appeal for a new hearing and decision. The Court of Appeal must now clarify whether the right of prior use includes the modification in accordance with the sub-claim, either because no additional advantage is associated with it or because it is an evident modification that can be considered without further ado.
