Prosecution history and infringement

01 June 2010

There are large differences between jurisdictions as to how and to what extent the prosecution history can be used later on in infringement and revocation actions for construing the patent in suit.

So far, Austrian courts have taken a balanced approach by using the prosecution history in cases where the meaning of a claimed feature was not totally clear, ie, not every word of the prosecution history was given automatic authority over other interpretations. However, if the patentee clearly defined a claimed feature in a restricting manner, he was subsequently bound to this restrictive interpretation taken during prosecution.

In one of its recent judgments the Austrian Supreme Court had to decide whether a patentee who restricted its claim during prosecution to a Swiss-type claim for manufacturing a pharmaceutical product is restrained from enforcing its patent against a defendant who claims that the product sold is not a pharmaceutical product but rather a dietary supplement. The defendant argued that the claims were clearly restricted to pharmaceutical products during prosecution, accordingly, the patentee waived any claims for dietary supplements. This defence was not found to be convincing by the Supreme Court.

Instead, the Court stated for the first time that, according to Article 69 EPC, the scope of protection is defined by the claims and the claims must be interpreted by taking into account the specification and the drawings; whether the prosecution history may indicate a more limited scope of protection is not relevant. In the Supreme Court's view the reason for this is that there is no guarantee that the prosecution history reflects everything that happened during prosecution; additionally the prosecution history may lead to further problems in the interpretation of the claims. In its judgment the Supreme Court also highlighted a proposal made during the Diplomatic Conference in November 2000 for the revision of the EPC to include the prosecution history as a means for interpreting the claims. The proposal did not win the support of a majority.

This Supreme Court decision, however, is contrary to Article 163(5) Austrian Patent Act which explicitly states that the content of the prosecution history has to be taken into account when construing the scope of protection. However, Article 163 only refers to declaratory actions filed with the Revocation Board of the Austrian Patent Office and not to civil court actions. As the civil courts are bound to the decision of the patent authorities, if a final decision in the declaratory proceedings is handed down before the final decision in the civil court action, the recent judgment may lead to contradictions in the construction of claims between a civil court action and a declaratory action filed with the Revocation Board.

Although this contradiction seems quite harsh at first sight, practically this contradiction should not lead to diverging results in most of the cases as usually a restriction of the claims during prosecution is caused by prior art. As the scope of protection can never be interpreted in such a broad way that something which is already prior art is also covered by the claims, the results in construing the scope of protection with or without taking into account the prosecution history should not diverge in too many cases. However, in civil case actions the defendant will not be able anymore to rely on the submissions of the patentee during prosecution, but must rather argue a restrictive interpretation on the basis of the relevant prior art in the future.