I NTRODUCTION <ul><li>Prosecution history estoppel , also known as file-wrapper estoppel , is a term used in United States patent law to indicate that a person who has filed a patent application , and then makes amendments to the application to accommodate the patent law, has no cause of action for infringement to the pre-amendment patent claims that were amended. The record made during the patent application process is known as the prosecution history and the practice of using this prosecution history to the chagrin of the inventor is known as prosecution history estoppel. </li></ul><ul><li>The following are 2 types of File wrapper estoppel: </li></ul><ul><li>Amendment Estoppel </li></ul><ul><li>Argument Estoppel </li></ul>
<ul><li>File Wrapper Estoppel essentially means that when an inventor during prosecution narrows down his/her invention to escape prior art by sum amendment, he/she cannot claim that someone else infringed his/her patent under doctrine of equivalence. </li></ul><ul><li>Doctrine of Equivalence: </li></ul><ul><li>The US Court made the famous statement that: A patentee may invoke this doctrine to proceed against the producer of a device “if it performs substantially the same function in substantially the same way to obtain the same result.” </li></ul>
<ul><li>Example: </li></ul><ul><li>Cloaks without fastening mechanisms are available. </li></ul><ul><li>Cloaks whose left and right side cannot be connected together. </li></ul><ul><li>(A) -invents a button to allow the sides of a </li></ul><ul><li>cloak to be held together. </li></ul><ul><li>“ A cloak with a front opening, a row of fasteners down </li></ul><ul><li>one side of the front opening and a row of holes at </li></ul><ul><li>corresponding locations down another side of the front </li></ul><ul><li>opening into which the fastener can be inserted” </li></ul><ul><li>Anyone selling cloaks with holes in which buttons can </li></ul><ul><li>be inserted -can be sued </li></ul>
<ul><li>(B) -invents mechanism with metallic hooks and a receptacle for placing the hooks; and obtains a patent“A cloak with a front opening having at least one metallic hook at one side of the front opening and at least one receptacle for said hook at the other side” </li></ul><ul><li>(C) -produces cloaks with fasteners, but instead of holes in the other side, provides loops made of string through which rectangular wooden buttons are to be put </li></ul><ul><li>(D) -produces “shirts” using the same buttons [fastener] as “A” but not “cloaks” </li></ul>
<ul><li>Applying DoE to the scenario </li></ul><ul><li>According to DoE, (C)literally infringes on all elements of (A) except on “the row of holes down the other side of the cloak” instead provided holes in the form of loops on the other side </li></ul><ul><li>1.These loops have the same function to act as the </li></ul><ul><li>receptacle for the fastener] </li></ul><ul><li>2.Using the loops same result is achieved [closing the </li></ul><ul><li>cloak] </li></ul><ul><li>3.In the same way [by putting the fasteners in the </li></ul><ul><li>corresponding receptacles] </li></ul><ul><li>So, using function-way-result test [DOE] (C) infringes (A) </li></ul>
Festo Corp Vs Shoketsu Kinzoku Kogyo Kabushyiki Co 535 US 722(2002) <ul><li>Facts: </li></ul><ul><li>Festo Corporation (petitioner) possessed patents for an industrial device. After Festo began marketing its device, Shoketsu Kinzoku Kogyo Kabushiki Co. (SMC, respondents) entered the market with a device that used one two-way sealing ring and a nonmagnetizable sleeve . Festo Corporation already owned two similar patents (although their initial patent application was rejected) for this industrial device. Festo filed suit, claiming that SMC's device was sufficiently similar that it infringed Festo's patents under the doctrine of equivalents . Festo's claim had been amended during prosecution for, at the very least, compliance with 35 U.S.C. §112, and thus Shoketsu claimed that prosecution history estoppel should bar Festo from asserting equivalents. </li></ul>
<ul><li>The United States District Court for the District of Massachusetts held that Festo's amendments were not made to avoid prior art, and therefore the amendments were not the kind that give rise to estoppel. A panel of the Federal Circuit affirmed. 72 F. 3d 857 (1995). The Supreme Court granted certiorari , vacated, and remanded in light of an intervening decision in Warner-Jenkinson v. Hilton Davis Chemical Co. . After a decision by the original panel on remand, 172 F. 3d 1361 (1999), the Federal Circuit ordered rehearing en banc , 187 F. 3d 1381 (1999). The court sitting en banc held that claim amendments made for compliance with the Patent Act presented a complete bar to claiming equivalents. </li></ul>
<ul><li>Issue: </li></ul><ul><li>Previously, any amendment to a patent application that narrowed a patent claim to comply with the Patent Act created an absolute bar to equivalents for the particular claim limitation that was narrowed by the amendment. </li></ul>
<ul><li>Court's decision: </li></ul><ul><li>The Supreme Court vacated the ruling made by the Federal Circuit , holding that such amendments do not create an absolute bar, but instead must be examined in light of the reason for the change </li></ul><ul><li>In particular, the Court held that patentee's decision to narrow claims through amendment in order to comply with the Patent Act automatically assumes surrender of the territory between the original claim and the amended claim, i.e., a presumption of surrendering all equivalents for the particular claim limitation that was narrowed by the amendment. The Court thus placed the burden on the applicant as to showing what equivalents were not surrendered. </li></ul>
<ul><li>Still, the Court conceded, however, that there are some cases where the amendment cannot be viewed as surrendering a particular equivalent. "The equivalent may have been unforeseeable at the time of the application; the rationale underlying the amendment may bear no more than a tangential relation to the equivalent in question; or there may be some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question. In those cases the patentee can overcome the presumption that prosecution history estoppel bars a finding of equivalence." </li></ul>
Conclusions <ul><li>In the absence of prosecution history estoppel, a patent provides protection broader than the literal language of the claim. The protection extends to accused devices that perform substantially the same function in substantially the same way to obtain the same result as the claims of the patent. </li></ul><ul><li>While initially designed to prevent fraud on a patent, the doctrine of equivalents has become an often used second method of proving infringement. </li></ul><ul><li>Thus the Doctrine of Equivalence may very well be a cancer on the patent system, and the Doctrine of Prosecution Estoppels is not the cure. </li></ul>
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