CASRIP Newsletter - Summer 1999, Volume 6, Issue 1
Federal Circuit's Struggle to Clarify the Protector's Scope of U.S. Patents after Warner-Jenkinson
by Toshiko Takenaka
Al-Site Corp v. VSI International Inc.1
Seal-Flex, Inc. v. Athletic Track & Court Construction2
In the past few months, the Federal Circuit has published a series of significant decisions which attempt to resolve difficult questions uniquely associated with claims drafted in the means-plus-function format. Such questions include (1) how to identify whether Section 112, Paragraph 6 applies to the language of the disputed element; and (2) whether a court should apply the doctrine of equivalents to an element in the means-plus-function format after finding no literal infringement. Because 35 U.S.C. Section 112, Paragraph 6 mandates courts to interpret claims in the means-plus-function format to cover only the structures in the specifications and their equivalents, this interpretation has resulted in a very narrow literal scope. Further, a recent case indicates no possibility of using the doctrine of equivalents with respect to means-plus-function elements.3 Therefore, parties had often extensively disputed whether the claim element falls within the scheme of Section 112, Paragraph 6.
The first question began to attract the attention of the patent community when Federal Circuit decisions revealed that various judges gave different weights to the presumption to apply Section112, Paragraph 6 when triggered by the claim drafter's selection of term "means" in claim language.4 Also, the Federal Circuit has applied Section 112, Paragraph 6 to claims defining the invention in terms of its function without using the term "means." This application has made it even more difficult to distinguish claims within the scope of Section 112 Paragraph 2 from others.
Al-Site5 was a perfect case to resolve both issues because they were squarely presented to the Federal Circuit. The patents-in-suit concerned a technology for displaying eyeglasses. To prevent eyeglasses being displaced from their display hangers, the patented format used a loop fastened on the eyeglasses with rivets or button and hole fasteners. The accused infringer had replaced the loop format with a hanger and adhesive extension (Product A), or a hanger with holes in the arms (Product B.) The patentee had drafted claims using the term "means," although some of the elements included extensive structural limitations. The district court nevertheless applied the rule of Section 112, Paragraph 6 to all elements with "means" term and construed them to cover only a rivet and button disclosed in the specification and their equivalents. Based on this claim construction, the jury found Product A literally infringing one of the patents-in-suit, and Product B infringing other patents under the doctrine of equivalents.
On appeal, the Federal Circuit examined whether the district court's claim construction in applying the rule of Section 112, Paragraph 6 was proper. Before analyzing the claims at issue, the Federal Circuit reinterpreted its own earlier decisions and clarified an analytical framework for courts to follow in construing claims in the means-plus-function format. The framework begins with a step of identifying whether the term "means" in a claim element was used in combination with a function. If a court answers the question affirmatively, the presumption applies and the claim element should be interpreted following the rule of Section 112, Paragraph 6.6 However, if the term "means" is combined with structural limitations instead of functional limitations, the presumption does not apply even if the patent drafter selected the term "means" which usually triggers the rule of Section 112, Paragraph 6.7 Even if the presumption applies, the patentee can overcome it by showing sufficient structural limitations to produce the function recited in the claim element.
With respect to infringement under the doctrine of equivalents by Product B, the parties' dispute centered on the "means for securing" element. The Federal Circuit found no error in applying the Section 112, Paragraph 6 rule because the element was drafted to use the term "means" in conventional means-plus-functional format as being combined with functional limitations without reciting sufficient structural limitations.
To address the question whether the jury's finding of no structural equivalent, but equivalent under the doctrine of equivalent is proper, the Federal Circuit first set forth two important differences between equivalents under Section 112, Paragraph 6 and the doctrine of equivalents. The first distinction was in regard to the development of the equivalent structure. An equivalent structure or act under Section 112, Paragraph 6 must exist at the time of patent issuance, but an equivalent under the doctrine of equivalents may include technologies developed after the patent issuance, but before the time of infringement.8 The second distinction focused on the degree of similarity in function. The substituted element in the accused device must perform the identical function, as recited in the claim element, to be structurally equivalent under Section 112, Paragraph 6. In contrast, under the doctrine of equivalents, an accused element need only perform substantially the same function as recited in the claim.9 However, the court admitted that both equivalence analyses apply similar tests of insubstantial difference. Thus, a substituted element that does not constitute the structural equivalent under Section 112, Paragraph 6, may also fail to meet the test for equivalent under the doctrine of equivalents.
Application of this analogy led to a conclusion that the jury's verdict for infringement under the doctrine of equivalents also supported the finding of structural equivalence under Section 112, Paragraph 6. In Al-Site, the holes in the arms of Product B existed at the time of issuance date and therefore did not involve an after-arising technology. The holes in Product B was held to perform a function identical to the loop with the rivet or button format recited in the disputed claim element because the parties did not dispute the issue of identical function. Since the analyses for structural equivalents and equivalents under the doctrine of equivalents are the same except for these two distinctions, the jury's finding of insubstantial difference under the doctrine of equivalents also supported a determination of insubstantial differences under Section 112, Paragraph 6. Thus, the Federal Circuit affirmed the jury's finding of infringement by Product B.
Following this framework, the Federal Circuit found some of the claim elements had sufficient structural limitations. Thus, the district court's application of the Section 112, Paragraph 6 rules to these elements were found to be erroneous. However, such errors were found to be harmless with respect to literal infringement by Product A. The jury found literal infringement based on narrowly construed claims by erroneously applying the Section 112, Paragraph 2 to some elements. The finding of literal infringement based on properly construed claims was sustained.
Although Al-Site provides a rule that a patentee can overcome the presumption of applying the rule of Section 112, Paragraph 6 to the "means" element by showing sufficient structural limitations, it is often difficult to distinguish whether the limitations are structural or functional. In Laitram,10 the Federal Circuit found some structural limitations as merely detailing the functions recited in the claim element. In Al Site, even Judge Ellis at the District Court for the Eastern District Court of Virginia, one of most patent experienced judges, failed to identify the distinction. The difficulty increases when applying the rule to elements in the step-plus-function format because of the fine distinction between acts an functions.
This difficulty was highlighted in Seal-Flex,11 in which both parties and the district court obviously confused the construction of "step-plus-function" elements with "means-plus-function" elements. The majority, nevertheless, did not touch upon the claim construction issue because the parties agreed to the district court's construction of step-plus-function elements, in applying the rule of Section 112, Paragraph 6 for means-plus-function elements. However, Judge Rader, the author of the Al-Site decision, believed that the parties did not agree with the construction, and that the resolution of this case requires the claim construction with proper application of Section 112, Paragraph 6. He wrote a concurring opinion to clarify the confusion, and gave a proper claim construction although he reached the same conclusion as the majority based on his construed claim.
In attempting to find a distinction between means- and step-plus function claim elements, Judge Rader emphasized one major difference: that "structure and material" are associated with "means-plus-function" elements while "acts" are associated with "step-plus-function" elements. With respect to "step-plus-function" elements, courts must use the same analytical framework applicable to "means-plus-function" elements in identifying whether the rules of Section 112, Paragraph 6 applies.
The use of term "steps" does not necessary invoke the application of Section 112, Paragraph 6. The rule applies only if a claim element is defined in terms of function and does not recite sufficient acts to perform the function. However, in determining whether a claim element recites sufficient acts, the difficulty exists in distinguishing limitations on acts opposed to limitations directed to functions. Judge Rader gives one criterion for the distinction: the phrase "steps of" generally indicates the introduction of specific acts, while the phrase of "step for" introduces functions triggering the presumption that Section 112, Paragraph 6 applies. Patentees can overcome the presumption when the element includes sufficient acts.
Similar to means-plus-function elements Section 112, Paragraph 6 may apply to an element that does not recite the "step for" phrase when the element merely recites underlying functions without reciting specific acts. Judge Rader defined "underlying functions" as the ultimate accomplishment of the elements, as distinguish from "acts" which involve the recitation of how to accomplish these functions. In sum, courts must carefully analyze limitations of elements at issue without "step for" terms to determine whether they fall within the scheme of Section 112, Paragraph 6, in the context of the overall claim and the specification.
Returning to the construction of method claims in Seal Flex, Judge Rader analyzed the "step of" elements and found that the rule of Section 112 Paragraph 6 is not applicable. However, he reached the same conclusion as the majority. Thus, the error made by the district court in construing the claim was harmless.
In Seal Flex, Judge Rader gave an important instruction to patent practitioners. To escape from the narrow claim construction resulting from step-plus-function construction mandated by the patent statute, claim drafters must avoid incorporating the words "steps for" and "means" which trigger the presumption. In recent decisions, Judge Rader repeatedly emphasized the importance of careful language choice in drafting claims and specifications.12 Since means- and step-plus-function claims were known to provide the broadest possible claim scope and loved by patent practitioners, there are millions of pending applications and issued patents including "means" or "step for" claim elements or using similarly unclear terminology with respect to whether to apply Section 112, Paragraph 6. The best approach to remedy the problem is to amend the claims. If amendment is not possible, an attorney should file a continuation if any application is pending, or file a re-examination if a patent has been issued. Otherwise, the court may punish patentees for their usage of such unclear terminology by applying the rule of Section 112, Paragraph 6, because patentee did not remove the problem of unclear claim drafting before enforcement when she could have done so.13
Setting aside the issues of whether the standard of sufficiency in structure, materials and acts in claim elements gives a clear cut answer to identify the application of the rule under Section 112, Paragraph 6, the message from the Federal Circuit is clear. If the language of claim is unclear, patentees are likely to be blamed and will probably lose favor with the courts. U.S. patent practitioners should now go to their clients and advise them to go to the additional expense of rewriting their claims to get rid of the once popular formats.
Further Confusion on the Application of Prosecu-tion History Estoppel: Does Festo Directly Conflict with Sextant?
Festo Corp. v. Shoketsu Kinzoku Kogyo K.K.14
*After completing this report, the Federal Circuit vacated the panel decision on Festo and granted en banc review.15
On April 19, the Federal Circuit published an opinion to affirm its infringement decision in Festo. Festo was the last of three Federal Circuit decisions16 vacated and remanded by the Supreme Court for further consideration in light of two important doctrines emphasized in Warner-Jenkinson17 limiting the application of the doctrine of equivalents. These two doctrines are the all elements rule, and the prosecution history estoppel. The Federal Circuit's review of the remanded case focused on the application of these doctrines.
Festo's two patents-in-suit, the Carroll and Stoll patents, are directed to magnetically coupled rodless cylinders used to repeatedly move articles a short distance, as used in assembly lines. The district court granted Festo's motion for summary judgement of infringement under the doctrine of equivalent with respect to the Carroll patent, but let the Stoll patent infringement claims go to the jury for final dispensation. The jury found infringement of the Stoll patent under the doctrine of equivalents. On appeal, the Federal Circuit affirmed both the summary judgement and the judgement based on the jury verdict.
On remand following Warner-Jenkinson, the Federal Circuit's review focus on the application of the doctrine of equivalents with respect to the pair of sealing rings situated at opposite ends of the piston in the Carroll patent. The accused infringer replaced the pair rings with a single two-way sealing ring situated at the end of the piston. That the substituted single sealing ring provided the same function, in the same way to produce the same result as the pair rings (providing a fluid tight seal with the cylinder), was not disputed. Instead, it was argued that the replacement of one component with two piece components does not satisfy the all elements rule emphasized by the Supreme Court in Warner-Jenkinson. It was further argued that the prosecution history estoppel prevents Festo from claiming infringement under the doctrine of equivalents with respect to the pair rings because Festo introduced the elements requiring the pair rings during the reexamination proceeding.
In reviewing the impact of Warner-Jenkinson on decisions dealing with the all elements rule, the Federal Circuit positively denied any basis for change in its well established case law for not requiring one-to-one correspondence of component between the accused device and claim.18 Otherwise, such restrictive application as proposed by the accused infringer would render the doctrine of equivalents meaningless. The Federal Circuit emphasized that compliance with the all elements rule is satisfied if the disputed claim element has a counterpart somewhere in the accused device or process. Because the Federal Circuit found the counterpart of the disputed element-the pair rings-which counterpart functions in the same manner to produce the same result as the disputed element, it found no violation of the all elements rule.
With respect to the accused infringer's argument that the prosecution history estoppel should apply, the Federal Circuit investigated the record of prosecution, particularly the reexamination proceeding. The court agreed with Festo that the disputed element was not introduced to distinguish a new prior art reference, Festo's own German patent, during the reexamination. The prosecution records revealed that Festo's argument to distinguish the reference focused on different elements. It was clear that Festo did not rely on the pair rings to distinguish the Carroll patent because the reference also disclosed the pair rings. Citing precedent limiting the application of estoppel to cases where applicants took a position relied on the disputed element to distinguish the prior art, the Federal Circuit declared that "a voluntary amendment, not accompanied by argument or representations relevant to patentability does not necessarily generate an estoppel, any more than do the claims as originally filed."19 Because the amendment adding the pair rings element was voluntary, the prosecution history estoppel does not apply. Thus, the Federal Circuit found no basis in its earlier decision for violating the all elements rule or the prosecution history estoppel remanded by the Supreme Court for reconsideration.
Festo seems to represent a type of situation that the Supreme Court in Graver Tank tried to prevent through the operation of the doctrine of equivalents, i.e., pirating an invention by introducing minor variations to conceal or shelter the piracy.20 In this instance the accused infringer simply replaced the pair rings in the claim with the single ring which is not literally covered by the claim. Pair rings were well known to those skilled in the art to perform the same function as the single ring. It is fair to say that the result reached by the Federal Circuit in affirming infringement under the doctrine of equivalents while denying the application of the prosecution is sound.
However, it seems that the Federal Circuit's ruling in Festo directly conflicts with its own precedent. In Sextant,21 a different three-judge panel ruled the prosecution history estoppel prevents any possibility of finding infringement under the doctrine of equivalents with respect to a voluntary amendment if the patentee cannot show a reason why the element was introduced during the prosecution. The facts and issues presented in Sextant closely parallels those in Festo. The disputed "metallization" limitation relevant to the substitution by the accused infringer was also introduced during the prosecution. Like Festo, the prosecution record clearly revealed the metallization limitation was not introduced to overcome the cited the prior art reference during the prosecution because the reference also disclosed the limitation. Nevertheless, the Sextant court applied the prosecution history estoppel, stating the presumption of the prosecution history estoppel applies when the other party refused to adopt the claim.
Like Sextant, in Festo there was no record to show a reason for introducing the pair rings element. The trial court judge called the reason for adding the rings was "a mystery." 22 The patentee in Festo avoided the prosecution history estoppel because there was no record to show the reason for the amendment while the patentee in Sextant was punished by the application of the estoppel for not keeping a good record on the prosecution. In short, the result of Festo for finding infringement under the doctrine of equivalents may be sound, but there is no doubt that Festo further confused interpretation of case law on the application of the prosecution history estoppel.23
Revival of Hypothetical Claim Approach
Streamfeeder LLC v. Sure-Feed Inc.24
A more effective doctrine to limit the application of the doctrine of equivalents is the prior art limitation discussed in Wilson Sporting Goods.25 In Wilson, Judge Rich explained that prior art restricts the range of equivalents because "a patentee should not be able to obtain, under the doctrine of equivalents, coverage which he could not lawfully have obtained from the PTO had he tried."26 To examine the extent of allowable coverage, he proposed to use "a hypothetical patent claim, sufficient in scope to literally cover the accused product and confirm if the PTO could have allowed the claim over the prior art."27
However, this hypothetical claim approach inherently introduces uncertainty in examining the range of equivalents because one can draft a number of hypothetical claims to literally cover the accused product. Because patentability depends on the form of claim chosen by the claim drafter, an answer to the question whether to allow the range of equivalents in context of the prior art also varies, depending on the form of the claim chosen to examine the coverage.
This defect of the hypothetical claim approach became clear in Streamfeeder in which one party advanced one hypothetical claim, while the other party advanced another claim. In Streamfeeders, the plaintiff, Streamfeeder, and the accused infringer, Sure-Feed, are competitors in the market of machines known as "bottom sheet feeders." Bottom sheet feeders collate paper and other thin materials for processing in a number of industrial applications, such as mass mailing, printing and binding. The parties' argument focused on the gate element, a cylindrical gate with grooves of different depths. Sure-Feed's feeder used an elliptical feed gate provided with grooves of uniform depth covered by a separate patent issued to Sure-Feed.
Because the shape and uniform grooves of the accused gate did not meet the limitations in the claimed gate element, Streamfeeder did not allege literal infringement. Instead, Streamfeeder alleged the accused gate with uniform grooves functioned in the same way to produce the same result as the claimed gate element. Both gates prevent double feeding by providing different friction force values through the surface of grooves. Sure Feed moved for summary judgement of no infringement, arguing the coverage to read on the accused feeder under the doctrine of equivalents would not be permissible because it read on the prior art. To respond to the argument, Streamfeeder presented a hypothetical claim. Since the district court found the hypothetical claim would have been patentable, it denied Sure-Feed's motion. The case was later tried before a jury which found that the accused device infringed Streamfeeder's patent under the doctrine of equivalents.
On appeal, Sure-Feed argued that the district court erroneously adopted the hypothetical claim advanced by Streamfeeder. Agreeing with Sure Feed, the Federal Circuit adopted another hypothetical claim, and found that the coverage sought by Streamfeeder was impermissible because its own hypothetical claim would read on the prior art.
Before resolving the issue of whether the prior art limits the coverage under the doctrine of equivalents, the Federal Circuit clarified the procedural question regarding which party carried the burden of showing coverage is permissible over the prior art. Case law on this burden was also unclear as to whether to impose the initial burden on the patentee, and as to what was required to meet the burden.28 The Federal Circuit explained the burden of going forward rested with the accused infringer, requiring him to produce a prior art reference, which limits the coverage. The burden of persuasion rests with the patentee by showing that the proper hypothetical claim is patentable over the prior art.
The Federal Circuit found the court erroneously adopted the hypothetical claim, not only because the lower court redrafted the claim at issue to literally cover the accused gate, but also because the court introduced new limitations on features that existed only in the accused feeder. According to the court, the hypothetical approach enabled the patentee to slightly broaden the coverage of the disputed claims, but would have never allowed narrowing of the claim to avoid the prior art. The privilege of redrafting claims is usually only granted during prosecution and other statutorily prescribed post-granting proceedings. Allowing the patentee to redraft the disputed claim in litigation would be contrary to the definitional and notice function of the claim.
The court applied this rule to the claim at issue in Streamfeeder, and only allowed redrafting to broaden the gate element to cover grooves to provide different friction force value. Because other features that distinguish in the prior art were eliminated from the hypothetical claim, the claim was too broad to sustain the patentability of the claim. As a result, the court reversed the district court's judgment, as the coverage sought by Streamfeeder under the doctrine of equivalents was impermissible.
This case presents an interesting contrast between the doctrines using the prior art to limit the doctrine of equivalents as developed in U.S. courts and German courts. In Streamfeeder, the Federal Circuit reemphasized the focus of it's examination was the claim, not on the accused product itself. In Germany, the Formstein defense, which is a counterpart doctrine of U.S. Wilson doctrine, allows courts to examine only the accused product or process, but not the claims at issue.29 Because validity determination is exclusive to the power of the German Federal Patent Court's jurisdiction, they are not allowed to examine the patentability of the claim itself. German courts are not even allowed to examine the patentability of the accused product, if the product falls within the literal scope of the claim at issue. It is not permitted because such examination would result in a reevaluation of the scope issued by German Patent Office, and lead to an invasion of the territory left exclusively to the Federal Patent Court. However, German courts are only allowed to examine the patentability of the accused product if it is outside the literal scope of the claim. Had the case been brought to a German court, German court would have upheld the hypothetical claim adopted by the district court.
Further, under German patent law, the burden to establish the Formstein defense is on the accused infringer. Although there is no clear distinction between the burden of going forward and that of persuasion under German law, both burdens rest on the accused infringer by requiring the production of prior art references and showing the accused product or process is not patentable over the references. Here, neither party met the burden.
The Japanese Supreme Court adopted a method to limit the doctrine of equivalent parallel to the Formstein defense and Wilson doctrine.30 Although the Court of Japan was unclear with respect to the adoption of this doctrine, it is likely to follow the German example since Japanese infringement proceedings follow the German tradition of separating jurisdictional power between the patent office and courts.31
The Wilson doctrine attracted the attention of the patent community, but was not widely adopted by accused infringers to avoid findings of infringement under the doctrine of equivalents. One possible reason for this unpopularity is that juries in infringement proceedings prefer to examine the accused product rather than a hypothetical claim. Recent developments have clarified that limitations on the doctrine of equivalents, including the Wilson doctrine, should be decided by the courts. In the future, judges may prefer to deal with legal concepts in regards to claims rather than the accused product.
Another possible reason is the difficulty in applying the doctrine. The application of Wilson doctrine necessarily leads to the difficult questions of the novelty and non-obviousness of the hypothetical claim over the prior art. Such questions lead to the analysis of complex issues regarding suggestion, motivation and analogous art. Thus, U.S. judges prefer to rely on the prosecution history estoppel which somewhat overlaps with the Wilson doctrine in limiting the coverage of equivalents in context of references cited during the prosecution. However, recent case law suggests that U.S. judges must examine the patentability issues in applying the prosecution history estoppel. The result is no lessening of the complexity for applying the prosecution history estoppel and Wilson doctrine. This case may indicate a return of the Wilson doctrine as an effective weapon to limit the doctrine of equivalents in U.S. courts.
1 Al-Site Corp. v. VSI Int'l, Inc., 50 U.S.P.Q.2d 1161 (Fed. Cir. 1999) reh'g en banc denied, 174 F.3d 1308, (Fed. Cir. 1999).
2 Seal-Flex, Inc. v. Athletic Track & Court Constr., 172 F.3d 836, 50 U.S.P.Q.2d 1225 (Fed. Cir. 1999).
3 Dawn Equip. Co. v. Kentucky Farms, 140 F.3d 1009, 46 U.S.P.Q.2d 1109 (Fed. Cir. 1998).
4 Cole v. Kimberly-Clark Corp., 102 F.3d 524, 41 U.S.P.Q.2d 1001 (Fed. Cir. 1996). (Judge Rader wrote a dissenting opinion, disagreeing with the weight given by the majority to the presumption of the Sec. 112, Par. 6 application when the draft has chosen a particular term "means.")
5 50 U.S.P.Q.2d 1161.
6 Greenberg v. Ethicon Endo-Surgery, 91 F.3d 1580, 39 U.S.P.Q.2d 1783 (Fed. Cir. 1996).
7 York Prods. v. Central Tractor Farm & Family Ctr., 99 F.3d 1568, 40 U.S.P.Q.2d 1619 (Fed. Cir. 1996).
8 Chiuminatta Concrete Concepts v. Cardinal Indus., 145 F.3d 1303, 46 U.S.P.Q.2d 1752 (Fed. Cir. 1998).
9 Cybor Corp. v. FAS Techs., 138 F.3d 1448, 1456, U.S.P.Q.2d 1169 (Fed. Cir. 1998).
10 Laitram Corp. v. Rexnord, Inc., 939 F.2d 1533, 19 U.S.P.Q.2d 1367 (Fed. Cir. 1991).
11 Seal-Flex, Inc. v. Athletic Track & Court Constr., 172 F.3d 836, 50 U.S.P.Q.2d 1225 (Fed. Cir. 1999).
12 Signtech USA, Ltd. v. Vutek, Inc., 174 F.3d 1352, 50 U.S.P.Q.2d 1372 (Fed. Cir. 1999).
13 50 U.S.P.Q. 2d at 1376 (Signetech could have filed a new application directed toward the species B invention without limitation in the specification or claims to the dual air sources. It did neither. Therefore, because of the statutory limitations governing the meaning of means-plus-function elements, courts must limit the scope of these claims to the corresponding structure disclosed in the specification and its equivalent.)
14 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 172 F.3d 1361, 50 U.S.P.Q.2d 1385 (Fed. Cir. 1999).
15 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., LTD., No. 95-1066, 1999 WL 636166 (Fed. Cir. Aug. 20, 1999).
16 The other two decisions which have been already published are (1) Litton Sys. v. Honeywell, Inc., 140 F.3d 1449, 46 U.S.P.Q.2d 1321 (Fed. Cir. 1998); and (2) Hughes Aircraft Co. v. United States, 140 F.3d 1470, 46 U.S.P.Q.2d 1285 (Fed. Cir. 1998).
17 Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 137 L. Ed. 2d 146, 117 S. Ct. 1040, 41 U.S.P.Q.2d 1865 (1997).
18 Corning Glass Works v. Sumitomo Electric U.S.A., Inc., 868 F.2d 1251, 9 U.S.P.Q.2d 1962 (Fed. Cir. 1989).
19 50 U.S.P.Q.2d 1393.
20 Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 94 L. Ed. 1097, 70 S. Ct. 854, 85 U.S.P.Q. 328 (1950).
21 Sextant Avionique, S.A. v. Analog Devices, Inc., 172 F.3d 817, 49 U.S.P.Q.2d 1865 (Fed. Cir. 1999).
22 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 172 F.3d 1361, 50 U.S.P.Q.2d 1385 (Fed. Cir. 1999).
23 Confusions introduced by Sextant were discussed in the author's report in published in 5-4 CASRIP Newsletter 1 (Center for Advanced Study and Research in Intellectual Property, University of Washington School of Law, Seattle, Winter-Spring 1999), available on-line at <www.law.washington.edu/~casrip /newsletter/newsv5i4us1.htm>.
24 Streamfeeder, L.L.C. v. Sure-Feed Sys., Inc., 175 F.3d 974, 50 U.S.P.Q.2d 1515 (Fed. Cir. 1999).
25 Wilson Sporting Goods Co. v. David Geoffrey & Assoc., 904 F.2d 677, 14 U.S.P.Q.2d 1942 (1990).
26 904 F.2d at 684.
28 Compare National Presto Indus. v. West Bend Co., 76 F.3d 1185, 1192, 37 U.S.P.Q.2d 1685 (Fed. Cir. 1996) with Wilson, 904 F.2d at 685. The unclear status of placing burden of proof for the permissible coverage of equivalents is discussed in a report by the author published in 3-3 CASRIP Newsletter 1(Center for Advanced Study and Research in Intellectual Property, University of Washington School of Law, Seattle, Fall 1996), available on-line at <www.law.washington.edu/~casrip/newsletter/newsv3i3us.html>
29 Moulded Curbstone (Formstein), 18 Int'l Rev. Indus. Prop. & Copyright L. 795 (1987) (BGH, 1986). For a general discussion of the German doctrine of equivalents, see Toshiko Takenaka, Interpreting Patent Claims: The United States, Germany and Japan, 17 Int'l Rev. Indus. Prop. & Copyright L. Studies 59 (1995).
30 Judgment of Supreme Court of Japan, Feb. 24, 1998. An English translation of the decision by this author is published in 5-1 CASRIP Newsletter 12 (Center for Advanced Study and Research in Intellectual Property, University of Washington School of Law, Seattle, Winter 1998), available on-line at <www.law.washington.edu/~casrip/newsletter/ newsv5i1jp1.html>.
31 A recent decision by the Tokyo High Court indicates a departure from this tradition. See, Judgment of Sept. 10, 1997 (Tokyo High Court). A report of the case by this author is published in 4-3 CASRIP Newsletter 6 (Center for Advanced Study and Research in Intellectual Property, University of Washington School of Law, Seattle, Fall 1997), available on-line at <www.law.washington.edu/~casrip/newsletter /newsv4i3jp3.html>.