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Infringement under the doctrine of equivalence

For assessing the scope of protection of a Patent (or a Utility Model) and for determining whether an accused product falls within the same, the claims of the respective IP-right have to be construed literally.  In some countries literal interpretation of a claim is broad in others it is narrow focusing on the exact working.

The latter is applied in German infringement cases in a first step and in a second step an infringement under the “doctrine of equivalence” is assessed, i.e., the wording of the claim is interpreted regarding the disclosure in the specification.

German courts apply a three-step test basically answering the following questions:

• Does the variant solve the underlying problem with means having the same effect (“gleichwirkend”)?
• Would the skilled person have realised the variant having the same effect?
• Are the considerations the skilled person takes into account for the variant close enough to the considerations for the literal solution, the variant to be considered equivalent?

Equivalence or no equivalence?
Typically the third is the knockout-question, wherein the answer is normally guided by considering whether the patent specification gives suggestions into the (equivalent) direction (z.B. BGH – “Diglycidverbindung” X ZR 69/10 13. Sept. 2011). The courts followed these considerations quite strictly, which resulted in a more limited scope of protection of claims in general for the last years. However, recently the BGH stepped back and ruled out that the interpretation of the scope of protection under the doctrine of equivalence is not limited to the explicit teaching of the patent specification (BGH – “Begrenzungsanschlag” X ZR 36/13 06. May 2014).

These developments in the interpretation of the scope of protection under German law should be taken into account when drafting and prosecuting an application:

• Claim all alternative embodiments described in the application otherwise to avoid that unclaimed embodiments are excluded from the interpretation of the claim.
• Do not disclose effective, equivalent embodiments, which will not be claimed (e.g., due to lack of unity).
• Avoid contradictions between claims and specification or drawings.
• Review specification and drawing critically if claims have been amended.

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