A patent grants its proprietor certain rights to exclude others from making use of all that falls within the ambit of the protection afforded by the patent claims. An encroachment of these rights is called a patent infringement. The cautious wording of these two sentences might arouse the reader’s suspicion that a lot of ifs and buts are involved until a patent infringement can be clearly assessed and damages can be collected.

The rights conferred upon a patentee by a patent are strictly limited to the territory of the country the patent was granted for. So far a patent infringement case has to be launched at a national court in the country where the patent is valid and where the infringement takes place. The decisions of the national courts are based on national law and national case law. Although the patent laws have been harmonized in Europe also in respect to patent infringement, it happens from time to time that the same subject matter is considered by an English court as a patent infringement of the UK patent and by a German court as not infringing the German patent, or vive-versa, even when the claims of the IK patent and the German patent are identical.

The German perspective

With about 600 patent infringement law suits per year Germany is in Europe the country with the highest numbers of infringement cases. This constitutes about 50% of all patent infringement cases in the European Community. In the UK only 50 cases are handled each year, due to the higher litigation costs involved in comparison to the cost of patent litigation in Germany. Due to the numerous case laws in Germany, it is very likely that the German case law will have a great influence on the cases decided in the future Unified Patent Court. In the following, as far as not explicitly mentioned otherwise, I use German case law to demonstrate the leading criteria that have been established by the Supreme Court (BGH) in patent infringement cases.

With the introduction of the European Patent Convention (EPC) and the adoption of these principles into national German Law the German courts had to substitute the former applied principle of a threefold approach (“Dreiteilungslehre”) by the new claim interpretation rules specified by article 69 EPC and the Protocol on the Interpretation of Rule 69. Apart that Article 69 refers to European patents or European patent applications, respectively and Article 14 of the German Patent Law refers to patents or patent applications in general, the wording is identical:

§ 14 PatG (in German)

Der Schutzbereich des Patents und der Patentanmeldung wird durch die Patentansprüche bestimmt. Die Beschreibung und die Zeichnungen sind jedoch zur Auslegung der Patentansprüche heranzuziehen.

§ 14 PatG (translated into English)

The extent of the protection conferred by a patent or a patent application shall be determined by the claims. Nevertheless, the description and drawings shall be used to interpret the claims.

Although the basics of Intellectual Property had been harmonized by international agreements, such as the Paris Convention for a long time, case law in respect to patent infringement traditionally had been developed differently. Therefore the fathers of the EPC felt the need to attach to the EPC instructions how to interpret Article 69. The two extremes in Europe were the British approach, which granted protection only close to the literal meaning of a claim, and the German approach, which would not only protect equivalents, but under certain circumstances also would protect the general inventive idea a person skilled in the art could have conceived from a patent.

Protocol on the Interpretation of Article 69 EPC

of 5 October 1973

as revised by the Act revising the EPC of 29 November 2000


Article 1 - General principles

Article 69 should not be interpreted as meaning that the extent of the protection conferred by a European patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. Nor should it be taken to mean that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patent proprietor has contemplated. On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties.


Article 2 - Equivalents

For the purpose of determining the extent of protection conferred by a European patent, due account shall be taken of any element which is equivalent to an element specified in the claims.

First step: Understanding the technical teaching of a claim

A patent is infringed when a third party makes use of the technical teaching of a patent as defined and limited by the claim(s) of this patent. Therefore the starting point for assessing an infringement and the construction of a cliam is always the technical teaching as a person skilled in the art would understand the technical teaching from the patent claim [1]. In a second step thereafter the extent to which a claim protects a technical teaching (the scope of protection), will be assessed.

In BGH X ZR 74/05 “Kettenradanordnung” the technical expert had interpreted the feature “tangential” in a strict mathematical sense and therefore had denied an infringement of the patent. As the patent description did not have any definition of “tangential” the technical expert argued that a person skilled in the art would have interpreted this feature in its strict mathematical sense. The Federal Supreme Court looked at the technical teaching of the invention and argued that by elaborating the technical teaching it would have become obvious that the feature “tangential” was used in a more general meaning, which was not restricted to the pure mathematical definition.

Second Step: Interpretation of the claim

Once the technical teaching of the claim is clear the next step is to interprete the wording of a claim. Since the introduction of Rule 69 EPC as legally binding for German claim construction a claim is now construed with respect to two aspects whether the claim is 

  • literally infringed (Wortsinngemäße Verletzung) or
  • equivalent infringed (Equivalente Verletzung)




Literal infringment (“Wortsinngemäße Verletzung”)

Literal infringement is not restricted to the wording (strict literal meaning) (“Verletzung dem Wortlaut nach”) or an ordinary or usual meaning of words of the patent claim. Literal infringement also comprises in addition hereto what meaning a person skilled in the art in view of the patent specification and the figures would attribute to the words of the claim [2]. However, the meaning of individual features serves only the purpose to assess step by step the determining overall meaning of the patent claim as a unit [3].

Claims characterize an invention globally. Therefore an example in the patent specification usually must not be used to limit the scope of a claim [4]. Even if the inventor tries to give an explanation why his invention works, this explanation (and the explanation may be even wrong) cannot be used to limit the scope of the claim to embodiments working according to the explanation [5]. In this regard it is important to know, that the German legal system does not allow to interpret claims to what was admitted by the applicant or argued by the examiner during the examination procedure or a nullification procedure. Only restrictions which have been added to the claim are relevant.

Usually a patent claim will be composed of features that are commonly known and features that manifest the invention with regard to the prior art. The inventor or applicant respectively is free to add features that do not contribute to the invention or have a common meaning. A common feature must not be attributed a special signification which goes beyond the usual literal meaning with the reasoning that the feature is there for a reason [6]. Unless explicetly expressed in the patent specification, the description and drawings may not be interpreted in a way to neither expand the scope of a claim nor in a factual limitation of the subject matter defined by the literal meaning of the claim [7]. In case the examples and the description refer to only a subset of examples which would be comprised by a claim, this must not limit the usual meaning of the wording of a claim to this subset. In no way it is admissable to limit the meaning below the usual meaning, unless the limitiation is contained in the description [8]

In the event a claim is ambiguous the person skilled in the art will use the patent specifications or the figures to deduce a useful meaning from the wording of the claim [9]. However, the wording of a claim has priority over the description. If patent claims and description contradict themselve, the description cannot be used to "correct" the claim [10].  What has not been explicetly claimed cannot fall within the protected scope of the patent.

The European Patent EP 0 575 970 claims a bag containing a liquid or solid concentrate for the production of a dialysing fluid. The further features of the claim are directed to specially designed coupling means for connecting the bag directly to a dialysis machine so that in contrast to prior art no hoses are needed.

The owner of this Patent started legal action against a competitor who was selling containers with concentrate for the competitor’s proprietary dialysis machines. The patent owner argued that all features of the main claim of his patent were literally infringed. The person skilled in the art will understand from the context of the patent that a container for concentrate has the same meaning as a bag. As an auxiliary request the patent owner claimed that the attacked embodiment at least makes equivalent use of the teaching of his patent, as the function of the bag is to provide a repository for liquid or solid concentrate. This object can be achieved in an identical way either by a flexible bag or by a container.

Although – as in the present case – when a term has a meaning in the current language, this meaning must not be applied without closer scrutiny. It must be borne in mind that a patent may not use a term in its meaning in the current language but is using a term in a different, for example in an extended meaning. As a patent is its own lexicon, not even the definitions in technical books should be used; a meaning of a feature in the claims has to be interpreted in view of the information given by the patent.

As a starting point the appeal court accepted the definition of a bag as a hollow, easily deformable object for holding other objects, which the plaintiff had submitted in his written statement of claim as the usual meaning of the term “bag”. Then the appeal court looked into the introductory part where the patent owner had discussed the prior art. As the prior art comprised rigid canisters and containers as well as bags. The difference between rather rigid containers and flexible bags was obviously known to the patent owner. When the patent owner, starting from this prior art defined the object of the invention to create a bag with small volume and weight the person skilled in the art will understand that the patent owner did not want to claim a rigid container but a bag in the usual meaning of the current language. As the walls of the container of the allegedly infringing embodiment are thick and stiff and may be deformed only with considerable force theses walls are not easily deformable.

Equivalent infringement

In case a patent is not infringed by the literal meaning of the claims, the claims may be infringed in a equivalent manner. It is well established case law that three criteria have to be fulfilled to establish equivalent infringement:

  1. the problem to be solved by the invention is solved with alternative ("abgewandelte") means, which objectively have the same effect ("gleichwirkend")
  2. the knowledge of the person skilled in the art enables the person skilled in the art to find the alternative means having the same effect
  3. the ideas explored by the person skilled in the art [in order to arrive at the solution having the same effect] must be based to such an extent on the meaning of the technical teaching that is protected by the claims, that the person skilled in the art considers the deviating solution with its alternative means as a solution having the same effect.

The first and the second criteria had been already established in a Supreme Court decision concerning an infringement of a European Patent enforced in Germany, when protocol to Art. 69 had to be taken into account the first time in Germany. The first criteria relates to if the solution is an equivalent solution whereas the second criteria excludes from the scope of equivalence for example alternative solutions which would constitute an invention in themselves. The third criteria seems to have been introduced 17 years later in a decision from 2002 (BGH "Schneidemesser I").                                                                                                                                                                                                                                                                                                                                                                                                                             

Rights granted by a patent

The rights granted by a patent depend whether the patent is infringed directly (§ 9 German Patent Law) or “only” contributory (§10 German Patent Law). As the patent law grants more rights against a direct infringer a patent owner would prefer to claim direct infringement rather than contributory infringement.

Direct Infringement

Article 9 German Patent Law

The patent has the effect that only the patent proprietor is entitled to use the patented invention. Any third party is prohibited, without of his consent to

  1. make, offer, put on the market or to use a product which is subject matter of the patent or to import or to own the product for these purposes;
  2. use a process which is the subject-matter of the patent, or, when the third party knows, or it is obvious in the circumstances, that the use of the process is prohibited without the consent of the proprietor of the patent to offer the process for use within the territory of this law;
  3. offer, put on the market, use, or import or own for these purposes the product obtained directly by a process which is subject matter of the patent.



Contributory Infringement

Article 10 German Patent Law

(1) The effect of the patent is furthermore that any third party is prohibited from offering or supplying within the territories of the law a person, other than those entitled to exploit the patented invention, with means, relating to an essential element of the invention for using the invention within the territory of this law without the consent of the patent proprietor, when the third party knows or if it is obvious in the circumstances that these means are suitable and intended for exploiting the invention.
(2) Paragraph 1 shall not apply apply when the means are staple commercial products, except when the third party induces the person supplied to commit acts prohibited by Article 9, sentence 2.
(3) Persons performing the acts referred to in Article 11 Number 1 to 3 shall not be considered to be parties entitled to exploit the invention within the menaing of paragraph 1

An alledged infringer cannot defend himself sucessfully, that the element he offers or sells and which is used within a patented product or system, is a usal, commercially available product, which was already known before the application date of the invention. For contributory infringement it suffices that the delivered product is an essential element of the inventive idea .

As essential elements are considered elements which functionally interact with other elements of the patented product to carry out the inventive idea. It is not uncommon that an invention is arranged exclusively by elements known from prior art or elements available as commercial products. The inventive idea, which has been awarded by a patent may reside precisely in the new arrangement of known elements achieving an inventive effect which is new and was not obvious at the time of filing the patent application.

However, by selling a product the patent protection may have been exhausted. If for example a party legally acquired a patented product, then the patent owner already benefited from his patent right by selling it exclusively at the first time. The patent owner therefore cannot interdict the further sale from the rightful owner to another party.

In the event the patent product needs repair due to its normal wear and tear before its usual lifetime ended, then the patent owner cannot hinder the repair of the patented product (BGH - Laufkranz "Flanged tyre"). This is different to a restoration of the patented product from used parts that have passed beyond their usual lifetime. In such a case the restoration of the product is equivalent of building a complete new product, which constitutes an infringement of the patent.



[1] BGH X ZR 74/05 “Kettenradanordnung” The features of a claim cannot be interpreted without having understood the technical teaching of a claim first.

[2] In BGH "Formstein" and shortly after in BGH X ZR 5/87 “Ionenanalyse”, paragraph 56 and 57 the Federal Supreme Court of Germany had the first time the opportunity to comment on the consequences of the protocol on the interpretation of Article 69: The understanding of the person skilled in the art affects already the identification and clarification of the meaning of the words used in a claim. … When assessing a patent infringement firstly the content of the patent claims has to be defined as a person skilled in the art would attach meaning to the wording of a claim. If the contested embodiment is making use of the assessed meaning of the claim, then the protected invention is used.

[3] BGH X ZR 82/03 “Drehzahlermittlung”

[4] BGH X ZR 44/84 – “Zuckerzentrifuge” for the old German Patent Law from 1968; affirmed by BGH X ZR 255/01 “Bodenseitige Vereinzelungseinrichtung” for the new German Patent Law which respects Art. 69 EPC.

[5] BGH X ZR 44/84 – “Zuckerzentrifuge”

[6] This argument may seem strange, but a patent appeal court used this argument to limit a feature of a claim to the strict literal meaning. In BGH X ZR 255/01 “Bodenseitige Vereinzelungseinrichtung” the Federal Supreme Court rejected this argument as invalid.

[7] BGH X ZR 255/01 Bodenseitige Vereinzelungseinrichtung”.

[8] BGH X ZR 131/02 “Schussfädentransport” related to an annullment of a patent. The examples might have involved an inventive step in view of the prior art. But as the patent owner had missed the opportunity to limit his claims, the meaning of the claims included also examples which were obvious to the person skilled in the art. The Federal Supreme Court saw no other way than to interprete the claims with their usual meaning and therefore had to nullify the patent.  

[9] BGH X ZR 275/02 “Zündkerze”

[10] In BGH X ZR 16/09 “Okklusionsvorrichtung" the claim explicitely referred to clamps adapted to clamp strands at the opposed ends of the device. The appeal court in error interpreted the claim that clamping (two) strands after they had been folded, so that they where situated on only one end of the device would fall within the meaning of the claim. The Federal Supreme Court admitted that the words "strands" and "clamps" could be understood as a generic term and may also refer to a single strand or a single clamp. But when the claim refers to "clamps at opposed ends of a device the claim stipulates two clamps.

[20] BGH X ZR 16/09 “Okklusionsvorrichtung