Infringement and Claim Construction: Towards a French File Wrapper Estoppel?

Patent infringement cases generally rely on the issue of claim construction. The crucial question facing the Courts is whether a specific feature of the claims is limited to the actual recitation of the claims or whether it actually may be extended to other embodiments. The French Courts tended to be reluctant to consider statements made by the Patentee during examination. They have recently changed their approach and considered the extent of amendments during examination when assessing the scope of the claims. On several occasions, the Courts considered that the integer introduced in the claims by the Patentee during examination is, as such, an essential feature of the invention and, hence, is limited to its actual language. Such deliberate limitation in the claims cannot be ignored and the scope of the claims should thus be construed accordingly. A prime example of a case where a limitation in a claim operated against the Patentee was established by the Paris Court of Appeal, back in 2003 (CA Paris, 4e Ch., Sept. 24, 2003). This case related to a device comprising only one rotary disk whereas the claim specified two disks. The Court of Appeal, considering that the integer "two disks" was not recited in the claim as originally filed and was added by the Patentee in response to the Preliminary search report, held that the device was thus not infringed. This decision is remarkable in that the feature introduced by the Patentee during examination did affect neither patentability nor the solution to the technical problem. Nevertheless, due to the mere fact that it had been introduced during examination, it was regarded as an essential feature of the invention. Similarly, in a first instance decision (TGI Paris, Nov. 30, 2004), the Paris Court dismissed an infringement action as an integer added by the Patentee in view of the Preliminary search report was absent from the alleged infringing device. More recently, the Paris Appeal Court confirmed these principles of claim construction (Cour d'Appel de Paris, 4e ch., April 5, 2006). Claim 1 of the patent in suit was amended during European examination by substituting the term "comprising" with "consisting" to overcome prior art objection. The absence of any features other than those specifically recited in amended claim 1 was considered by the Court as an essential feature of claim 1. This opened to dismissal of the infringement action. The French Courts have recently affirmed the prosecution history estoppel. As a result, any amendment made during examination, whether or not made to overcome prior art, renders the feature thus introduced essential. This approach crucially affects patent practice: those preparing infringement opinions should examine the file history in order to correctly assess the scope of the claims. On the other side, patent prosecution should be carefully conducted so as to make sure that any scope of protection is not surrendered during examination. Stéphanie Michiels