Protective coating

Published on 31st Mar 2020

With its recent decision regarding the right of prior use for patents (BGH, judgment of 14 May 2019 - X ZR 95/18 – Schutzverkleidung) the German Federal Court of Justice (Bundesgerichtshof, BGH) clarifies the scope and limitations of admissible patent use and ensures more legal certainty.


Plaintiff in the case at hand is the proprietor of a patent for protective covering for radio systems and a method of its fabrication. The defendant manufactures and installs the patented protective covering for his clients. Prior to the filing date of the patent in dispute, the defendant has already manufactured individual components for such protective coverings and supplied these components to third parties, who then assembled the components to form the protective coverings by themselves. Therefore, defendant denied infringement with a so-called right of prior use.

According to Sec. 9 of the German Patent Act, only the patentee shall be entitled to use the invention protected by the patent. This prohibition shall not apply in respect to a person who, at the time of filing the application, had already begun to use the invention in Germany or had at least “invested” by making the necessary arrangements for doing so (Sec. 12 para 1 of the German Patent Act). With this right of prior use, the law intends to protect a business, that has already been in the innovation phase at the time of the patent application and that therefore has spent time and money in the implementation of the technical teaching.

However, the prior use is essentially limited to the status of development given at the priority date. On the other hand, developments that are more complex are generally not allowed, as well as more intensive uses or uses in a different way. For that reason, any exceeding of this legal protection constitutes an infringement of the patent. However, the specific scope of the right of prior use has not been finally clarified in this context yet.

With the present decision, the BGH confirms the judgment of the Higher Regional Court (OLG) Düsseldorf, that dismissed the first-instance infringement action on appeal (OLG Düsseldorf, judgment of 14 March 2018 - I-15 U 49/16).

The decision of the BGH

Even though the defendant has used the technical teaching of the plaintiff's patent, the defendant may invoke a right of prior use in the specific case. The BGH states that the use of the invention does not exceed the scope of the right of prior use and specifies the legal standards for admissibility of modifications of the prior use at the same time.

According to the BGH the legitimate interests of the prior user with regard to the investments already made on the one hand, and the scope of the patentee's prohibition rights on the other hand, must be assessed via interpreting the patent claims under consideration of the patent description and drawings. If two equivalent alternatives for a feature are mentioned in a patent claim, the fact that the prior user only used one alternative should as a rule not result in any disadvantages for the prior user. Variations of prior use disclosed in the patent specification, which are obvious for the skilled person at the time of application or priority date, are usually considered not to infringe patent rights. In contrast, modifications which are protected as an additional advantage of the invention in sub-claims or which are particularly emphasised in the description are not covered by the right of prior use, if this way of use had not also been started or at least concretely prepared before the priority date.

Concerning the way of use, the manufacturer of individual components which were originally assembled by third parties to form the entire device may also invoke an equivalent right of prior use if the contested embodiment is now completely manufactured by himself. This requires that the individual components in question technically and economically can only be assembled to the entire device in accordance to the invention. According to the BGH, that case also constitutes a direct use of the technical teaching regarding manufacturing and not only an indirect use regarding supplying to third parties. As long as the method claim of a patent teach no more than the only technically and economically sensible assembly of the entire device, the prior user shall also be entitled to (directly) use this method protected by the patent.

Moreover, if the prior user has used the subject-matter of the invention in at least one instance before filing or an applicable priority date, it is not necessary for creation or the maintenance of the prior use right that the use is continued constantly. The right of prior use only lapses once the prior user abandons this right. In this regard, the circumstances of the individual case are relevant; a temporary interruption of usage (in the specific case more than ten years) is not sufficient.

Practical note

If arguments for a non-infringement are not available, prior use rights are an effective defence in patent infringement proceedings. However, for good reasons the success of this defence is subject to strict conditions in jurisprudence. As soon as the prior user (slightly) modifies his possession of the invention, he generally leaves the safe harbour of prior use. Problems arise especially in triangular constellations or after the assignment of parts of business. In this context, the decision of the BGH provides further legal certainty. The patent claims as well as the patent description and drawings are used to determine the scope of the right of prior use. This is consistent, as the same approach is followed when assessing patent infringements. Therefore, the prior user is now able to carry out modifications to his technical solution already used before the filing date within the boundaries of the technical teaching disclosed in the patent. Accordingly, a legitimate later variation of use is not per se excluded. In addition, the BGH transfers the legal principles established for the assessment of a direct use regarding the manufacturing to the determination of the scope of the prior use right. The decision likewise ensures legal certainty in this regard. This is especially welcome from the perspective of the prior user.

However, the decision still leaves room for patent applicants to impede the prior use defence. Modified embodiments may be excluded from the right of prior use by using skilful wording of patent claims (in particular additional independent patent claims and dependent sub-claims) and/or emphasising technical advantages in relation to these claims. In that case, it is uncertain whether it is sufficient for a successful defence to state that the alleged advantage is not at all based on an inventive step. Actually, the BGH unfortunately did not decide to what extent further developments or different uses are generally covered by the right of prior use if they are obvious to a skilled person having the knowledge of the prior user and not requiring an inventive step.

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* This article is current as of the date of its publication and does not necessarily reflect the present state of the law or relevant regulation.

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