Prosecution history estoppel, also known as file-wrapper estoppel

Estoppel

Estoppel in its broadest sense is a legal term referring to a series of legal and equitable doctrines that preclude "a person from denying or asserting anything to the contrary of that which has, in contemplation of law, been established as the truth, either by the acts of judicial or legislative...

, is a term used in United States patent law

United States patent law

United States patent law was established "to promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries;" as provided by the United States Constitution. Congress implemented these...

 to indicate that a person who has filed a patent application

Patent application

A patent application is a request pending at a patent office for the grant of a patent for the invention described and claimed by that application. An application consists of a description of the invention , together with official forms and correspondence relating to the application...

, and then makes narrowing amendments to the application to accommodate the patent law, may be precluded from invoking the doctrine of equivalents

Doctrine of equivalents

The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed...

 to broaden the scope of their claims to cover subject matter ceded by the amendments.

Although primarily a U.S. term, questions of whether, or the extent to which the prosecution history should be relevant for determining the extent of protection of a patent also arise outside the U.S.

United States

The defining case on prosecution estoppel in the United states is Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 , was a United States Supreme Court decision in the area of patent law that examined the relationship between the doctrine of equivalents Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), was a United States...

.

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Court of Appeals for the Federal Circuit Holding

In November 2000, the Court of Appeals for the Federal Circuit set a complete bar rule. This complete bar rule completely prohibited a patent owner from asserting the doctrine of equivalents

Doctrine of equivalents

The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed...

 for certain elements of his claim in instances where, during his patent prosecution he files:

1. an amendment that narrows the scope of a claim for any reason related to the statutory requirements for a patent will give rise to a complete bar with respect to the amended claim element;
2. a "voluntary" claim amendment that narrows the scope of the claim for a reason related to the statutory requirements for a patent will give rise to prosecution history estoppel as to the amended claim element; and
3. an amendment and fails to explain the reasons for the amendment during prosecution of his patent.

Supreme Court reversal

The United States Supreme Court in their opinion Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 , was a United States Supreme Court decision in the area of patent law that examined the relationship between the doctrine of equivalents Festo Corp. v Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), was a United States...

, 535 U. S. 722 (2002), citing the instruction in Warner-Jenkinson Company, Inc. v. Hilton Davis Chemical Co.

Warner-Jenkinson Company, Inc. v. Hilton Davis Chemical Co.

Warner-Jenkinson Company, Inc. v. Hilton Davis Chemical Co., 520 U.S. 17 , was a United States Supreme Court decision in the area of patent law, affirming the continued vitality of the doctrine of equivalents while making some important refinements to the doctrine.-Facts:The plaintiff Hilton Davis...

, found that "courts must be cautious before adopting changes that disrupt the settled expectations of the inventing community," overturned the complete bar issued by the Federal Circuit. It also acknowledged that while any narrowing amendment made for a reason related to patentability could give rise to prosecution history estoppel, inventors who amended their claims under the previous case law had no reason to believe that they were conceding all equivalents of amended elements when responding to a rejection. Had they known, the Court stated, they might have appealed the rejection.

With this policy in mind, the Court stated that it preferred a presumptive bar approach to the doctrine of equivalents. This presumptive bar approach holds that where claims are amended, "the inventor is deemed to concede that the patent does not extend as far as the original claim" and the patentee has the burden of showing that the amendment does not surrender the particular equivalent. To succeed, then, the patentee must establish that:

1. the equivalent was unforeseeable at the time the claim was drafted;
2. the amendment did not surrender the particular equivalent in question; or
3. there was some reason why the patentee could not have recited the equivalent in the claim.

Free World Trust v. Électro Santé Inc. (2000)

This leading case in Canada on the issue of file wrapper estoppel, confirmed the emphatic rejection of this doctrine in Canada, as seen in previous cases, such as Lovell Manufacturing Co. v. Beatty Bros. Ltd. (1962). In Canada, no distinction is drawn in this regard between cases involving allegations of literal infringement and those involving substantive infringement. This means that the negotiations that have taken place between the patentee and the Patent Office cannot be used in order to establish a particular equivalent. Similarly, a patentee is barred from using any previous negotiations with the Patent Office in order to determine the scope of the claims of the patent (i.e. the negotiations cannot be used by the patentee or against the patentee in determining the scope of the claims within the patent).

Germany

The German Supreme Court, the Bundesgerichtshof, ruled in 2002 that "For the determination of the extent of protection of a patent, occurrences in the examination proceedings which preceded the grant in principle are irrelevant".

Ireland

The Irish Supreme Court has ruled that "evidence from the file which reflects the views of the patentee as to the construction of the claims is inadmissible".

Netherlands

The Dutch Supreme Court has effectively come to the opposite conclusion to most other countries in Europe. The Dutch Supreme Court has stated that where "a third party invokes the examination file in the course of confirming the interpretation defended by him of a patent, it cannot be seen that that requirement [the reasonable doubt threshold] would force any restriction on involving public data from the examination file with the interpretation of the patent".

United Kingdom

The UK Courts have ruled that use of the examination file in aiding construction of a patent should be discouraged except where that file includes "objective information about and commentary on experiments".