The IPKat is most grateful for this interesting piece, noting that in the UK we don't seem to have either a doctrine of equivalents (whatever the Protocol to Article 69 EPC may say) or prosecution history estoppel.
Swedish Appeal Court applies prosecution history estoppel in the Swedish part of a multinational dispute
In a judgment issued this spring, a Swedish Appeal Court confirmed that a (type of) prosecution history estoppel can bar a finding of infringement under the doctrine of equivalents.
The background to this case was that AGA Medical had the European patent EP 0 808 138, directed to an intravascular occlusion device and a method for manufacturing the same. Occlutech sold a product – the "Figulla Occluder" – used for sealing (occluding) e.g. holes in the walls separating the chambers of the heart.
Occlutech sued AGA for a declaration that the Figulla Occluder did not infringe AGA’s patent, and AGA sued Occlutech for an injunction against the Figulla Occluder.
The District Court sided with Occlutech and found that the Figulla Occluder did not infringe the patent.
AGA appealed the case, and the Appeal Court ruled on a number of issues. The perhaps most interesting question was whether the Figulla Occluder fulfilled a claim element providing that “clamps are adapted to clamp the strands [forming a metal mesh] at the opposed ends of the device”.
|This is the Figulla Occluder|
The Appeal Court then went on to consider the doctrine of equivalents. AGA had added this particular claim element during prosecution as a characterizing feature to distinguish the claimed invention from certain prior art disclosing a similar device with two open ends. In particular, AGA had stated that the amendment was made “to clarify this distinction over the prior art”. The Appeal Court felt that this made it clear that AGA must have considered it to be essential for the patentability that the device was closed by a fixation of the strands at both ends. The element was in other words essential in connection with the grant of the patent. This spoke strongly against expanding the scope of protection to encompass a product that differed from this element of the claim. This was despite the fact that when making the amendment AGA alleged that the unamended claim was in any case distinguished over the prior art
Hence there was no room for applying the doctrine of equivalents here. AGA could not distinguish the claimed device over the prior art by specifying that the strands were fixated at both ends and then come back and contend that a product where the strands were only fixated at one end infringed.
(Interestingly, however, the Appeal Court interpreted another term in the very same – essential – claim element beyond its literal meaning. According to the Court, the claim term “clamps” included welds to keep the strands together. The Court does not seem to have regarded this as an application of the doctrine of equivalents, but rather as a “functional”, “contextual” or “purposive” interpretation.)
The Appeal Court’s ruling accordingly confirms the established practice in Sweden. The courts here have applied a form of prosecution history estoppel for a long time. As an example of this, the Swedish Supreme Court stated in a case from 2002 that “material from the prosecution history should be used to interpret unclarities in patent claims and description when it is a question about a limitation of the scope of protection” (my English translation).
Last, it might be interesting to note that the courts in Germany, the Netherlands and the UK have also decided on this case, with different ways of reasoning. The courts in the Netherlands and the UK found that there was no infringement. In Germany, the Appeal Court in Düsseldorf held that there was an infringement, but the Federal Court of Justice reversed the decision.