CASRIP Newsletter - Fall 1996, Volume 3, Issue 3
New Legislation and Case Developments
Patent Limitations on Medical Procedures
On September 30, 1996, President Clinton signed into law legislation exempting medical practitioners and related health care entities from infringement liability under the Patent Act for the performance of patented surgical or medical procedures that do not involve drugs or devices. Prompted by recent increases in the enforcement of patents for therapeutic and diagnostic methods as well as corresponding concerns that such patents restrict access to medical procedures and increase the cost of health care, this new legislation represents the final compromise among various bills introduced throughout the past year regarding medical procedures patents.
The medical procedures reform amends section 287 of title 35 of the United States Code, the patent statute's provision on damages limitations, by adding the following subsection:
(c)(1) With respect to a medical practitioner's performance, of a medical activity that constitutes an infringement under section 271(a) or (b) of this title, the provisions of section 281, 283, 284, and 285 of this title shall not apply against the medi cal practitioner or against a related health care entity with respect to such medical activity.
Subsection (c)(2) defines "medical activity" as "the performance of a medical or surgical procedure on a body," but excludes:
(i) the use of a patented machine, manufacture, or composition of matter in violation of such patent, or
(ii) the practice of a patented use of a composition of matter in violation of such patent, or
(iii) the practice of a process in violation of a biotechnology patent.
Additionally, subsection (c)(2)(F) provides that "the term 'patented use of a composition of matter' does not include a claim for a method of performing a surgical procedure on a body that recites the use of a composition of matter where the use of that composition of matter does not directly contribute to achievement of the objective of the claimed method." Moreover, according to a conference committee summary, it does not prohibit remedies where the claim in a patented use of a composition of matter co ntributes to the novelty of the claimed method. Such uses include "novel uses of drugs, novel uses of chemical or biological reagents for diagnostic purposes, novel methods for scheduling or timing administration of drugs, novel methods of combining drug therapies, and novel methods for providing genetic or other biological materials to a patient (including gene therapies)."
Finally, section (c)(3) clarifies that the new reform does not exempt persons "engaged in the commercial development, manufacture, sale, importation, or distribution of a machine, manufacture, or composition of matter."
Advocates of the new legislation assert that the purpose of the reform is to prevent health care professionals from being sued for using innovations in pure medical or surgical procedures, such as the Heimlich maneuver or CPR. Moreover, they argue for th e necessity of such legislation in view of the concern that widespread enforcement of medical procedures patents would lead to significant increases in health care costs, accessibility and enforcement problems, and distortions of medical research and pati ent-physician relations. Furthermore, they stress that because the reform does not change the current patent law for biotechnology, medical devices, drugs or their methods of use, it would not discourage important research conducted in those areas.
Opponents to the new legislation, however, have expressed reservations about the medical procedures provisions. They argue that the practical effect of the added provisions on damages limitations is to preclude an important class of endeavor - medical pr ocedures - from protection under section 101. Additionally, they express concerns that the new reform may be inconsistent with the United States' GATT-TRIPS obligations.
Facially at least, the new reform does not seem to violate the U.S.'s international treaty obligations. Although Art. 27 of TRIPs requires that members grant patents "in all fields of technology," Art. 27(3)(a) allows member states to "exclude from paten tability diagnostic, therapeutic and surgical methods for the treatment of humans or animals." Similarly, Art. 1709(3)(a) of NAFTA permits a member country to exclude from patentability diagnostic, therapeutic and surgical methods for the treatment of hum ans or animals.
It is interesting to note, however, that the new legislation amends the provisions on damages limitations and not patentability requirements. Therefore, the Article 27 provisions in TRIPs regarding patentable subject matter may not be the issue here, but rather the provisions on rights conferred and damages. Even then, the new legislation does not appear to be inconsistent with the treaty which does not prohibit restrictions on the rights conferred which are reasonable. Rather, the new provisions bring U .S. patent law closer to those of other major industrial countries, such as Japan, Canada, and the members of the EPC, which already deny patent protection to therapeutic and diagnostic methods on the grounds that such patents violate public policy.
Trade Secrets Law Criminalizes "Economic Espionage"
On October 11, 1996, President Clinton signed into law legislation which criminalizes "economic espionage" and classifies the theft or misappropriation of trade secrets as a federal crime. Recognizing the growing importance of intellectual property to th e American economy and the increasing concern about the relative ease with which "economic espionage" can be perpetrated in the information age, the new reform extends federal protection to yet another form of proprietary economic information - trade secr ets.
The Economic Espionage Act of 1996 was prompted by the lack of adequate protection under federal law for trade secrets and the subsequent difficulty in prosecuting thefts involving this type of information. The reform establishes a comprehensive and syst ematic approach to trade secret theft and economic espionage, thus facilitating investigations and prosecutions. In effect, the new legislation strengthens protection for the National Information Infrastructure in the United States by addressing attacks against computer networks and the information they contain.
The new law amends title 18 of the United States Code by creating a new chapter 90, entitled "Protection of Trade Secrets." The new law identifies two types of criminal trade secret misappropriation: 1) that which is intended to benefit a "foreign govern ment, foreign instrumentality, or foreign agent;" and 2) that which is intended to benefit individuals and corporations.
More specifically, under section 1831, which is aimed at "economic espionage" intended to benefit a foreign government, offenses would be punishable by fines of up to $500,000 and/or imprisonment of up to 15 years, with offending organizations being subj ect to fines of up to $10,000,000. Similarly, under section 1832, which is aimed at "theft of trade secret," offenses would be punishable by criminal fines and/or up to 10 years imprisonment, and would subject organizations to fines of up to $5,000,000.
The legislation applies to conduct occurring within the United States as well as to conduct abroad, if the offender is: 1) a U.S. citizen or permanent resident alien; or 2) an organization "organized under" federal, state or local laws. Acts outside the United States are also covered if an act in furtherance of the offense was committed in the United States.
Additionally, the reform provides for criminal forfeiture of the proceeds of the crime and limited forfeiture of the property used to commit the crime. It also requires courts hearing cases brought under the statute to enter such orders as may be necessa ry to protect the confidentiality of trade secrets. Finally, the new law authorizes the government to obtain injunctive relief and establishes exclusive jurisdiction in federal district court.
- Maria Trinidad Arriola
The year of 1995 was definitely a productive year for the Federal Circuit which issued the landmark en-bank decisions, Markman, Hilton Davis, and Rite Hite. All three decisions significantly impact the direction of case law in relation to claim interpretation, the application of the doctrine of equivalents, a nd the scope of damages in terms of lost profits. Recent cases have begun to refine the holdings of the court in those decisions.
Increased Significance of Specification for Claim Construction
Since Markman clarified the judge's role in interpreting claim language, the Federal Circuit clarified the significance of claim interpretation aids. In Vitronics Corp. v. Conceptronic, Inc.,  Judge Michel refined the framework for analyzing infringement issues developed in Autogiro Co. of America v. United States, emphasizing that courts must always review the specification. The most important refinement of the Autogiro framewo rk is a classification of claim interpretation aids on which courts may rely when interpreting claims depending on their weights. In construing claim language, courts should give more weight to intrinsic evidence, including the claims, the specification and the prosecution history over extrinsic evidence which includes dictionary definitions, prior art and expert testimony. The underlying policy is legal security. Claim interpretation becomes part of the public record on which people are entitled to rel y when ascertaining the scope of patented inventions and designing around those inventions.
Accordingly, reliance on any extrinsic evidence is improper when the intrinsic evidence unambiguously determines the claim scope. Even in those exceptional cases where the scope remains ambiguous after viewing all intrinsic evidence, expert testimon y should be given the least weight compared to dictionaries, scientific treatises, and prior art. This is because the public has no access to the expert testimony evidence until it is introduced at trial. Furthermore, expert testimony may not be used to contradict claim language or other parts of the specification. This suggests that in a Markman hearing for determining the meaning of disputed claim terms, a party's arguments should be supported by intrinsic evidence.
The use of the prior art after Vitronics Corp. remains somewhat unclear. With respect to the prosecution history, Judge Michel in dicta, discussed the use of prior art as being intrinsic evidence. However, he later classified the prior art a s extrinsic evidence, whether or not cited in the specification or file history. So issues such as whether one can rely on another part of a reference rather than the part cited in the prosecution is unclear. This classification of the prior art dependi ng on whether a prior art reference is cited is interesting from a comparative law perspective because it parallels the classification of the prior art in German claim interpretation, particularly with respect to jurisdictional separation between infringe ment and patent courts.
As a result, the significance of the specification in interpreting patent claims has notably increased. Although the specification has always been the primary source in resolving disputes over the meaning of claim language even prior to Markman, recent cases indicate a tendency to decide the meaning of disputed language by simply making reference to the embodiments in the specification. It follows that despite an the applicant's effort to select general claim terms to cover a broader literal protection scope than that expressly disclosed by the embodiments in the specification, such efforts are often meaningless.
In Texas Instruments, Inc. v. Cypress Semiconductor Corp.,,  the issue in dispute was whether the claim term "conductor" includes the defendant's "die pad". In the defendant's more advanced IC, the semiconductor device wa s attached to a lead frame at a die pad, instead of a conductor strip extending from inside the package of the semiconductor device to the outside, as disclosed in the specification. The Federal Circuit rejected TI's argument, which relied on the broad d ictionary meaning of "conductor" being any structure capable of conducting electricity, instead agreeing with the district court that the term "conductor" in disputed claims covers only constructions extending from inside the package to the outside and co nnecting the semiconductor device to an external circuit. The Federal Circuit found that the disclosure in the specification supported this interpretation. Failing to produce evidence to show that the defendant's die pad extending from the semiconductor device to an external circuit, TI could not establish literal infringement and its attempts to cover future modifications by adopting a general term such as "conductor" were ineffective.
In more and more cases, embodiments have begun to play an important role in claim interpretation. In Hoechst Celanese Corp. v. BP Chems. Ltd.,  the patented invention was a method for reducing iodide contamination in an organic medium such as acetic acid, by adding a macroreticulated silver-charged cation exchange resin. The claim required the resin to be stable in the organic medium. The specification provided a definition of "stable" being that the resin would not de compose or change more than about 50% from its dry physical dimension. Since resin in the defendant's process changes more than 50% in volume but less than 50% in linear dimensions, the parties disputed the meaning of the term "dimension." Unlike Judge Michel in Vitronics Corp., Judge Newman, indicating her frustration concerning the limited use of expert testimony imposed by Markman, thoroughly reviewed testimony offered by each party to support alternative interpretation and the diction ary definition. Despite giving weight to such extrinsic evidence, she finally resorted to the specification, noting that the defendant's interpretation of "stable" meaning dimension by volume would exclude the patentee's preferred embodiment.
In short, the Federal Circuit's focus on intrinsic evidence, particularly the specification, is motivated by procedural economy. By determining the literal claim scope in the early stages of litigation, it attempts to solve infringement disputes wit hout the aid of expensive, hired-gun experts. This inevitably limits claim interpretation to cover what is implicitly disclosed to one skilled in the art. Thus, where the accused device or process is not exactly the same as any of the embodiments disclo sed in the specification, patentees must rely on arguments based on infringement under the doctrine of equivalents, rather than on literal infringement.
Doctrine of Equivalents after Hilton Davis
On October 15, 1996, the Supreme Court held a hearing to review the Federal Circuit's en bank decision, Hilton Davis Chem. Co. v. Warner-Jenkinson Co. The Federal Circuit's ruling on the doctrine of equivalents requiring an "insubstantial difference" between the patented invention and the accused product or process has generated significant criticism. The most common criticism is that the "insubstantial difference" standard will increase the inheren t uncertainty of the application of the doctrine of equivalents. Many patent practitioners complained about the unpredictability of infringement results should the doctrine be applied in the liberal scope indicated by the Hilton Davis majority.
The "insubstantial difference" standard, which focuses on the substantial function/way/result identity and known interchangeability to one skilled in the art, is comparable to the test for finding equivalency long adopted by German courts and Europea n jurisdictions which follow the German claim interpretation tradition. Contrary to criticisms from U.S. practitioners, German practitioners are accustomed to dealing with some uncertainty resulting from courts' claim interpretation. They are however, quite concerned about insufficient protection when the courts protect only what is literally claimed.
In German patent infringement litigation, the parties' dispute usually centers around the determination of equivalency, rather than the construction of claim language. This is so because courts tend to interpret the meaning of claim language relying heavily on the disclosure in the specification, rather than on the dictionary definition or expert testimony. This somewhat parallels recent trends in the Federal Circuit after Markman, construing claims relying on intrinsi c evidence, particularly the specification.
Despite a number of amicus briefs submitted by professional associations and industries requesting to limit the scope of the doctrine's application, the Supreme Court's inquiries focused on the policy reasons necessiting the application of the doctri ne and the application of prosecution history estoppel to limit the doctrine, rather than the standard for finding equivalence itself. Both parties submitted their arguments supporting the necessity or requesting the elimination of the application of the doctrine and explained why prosecution history estoppel should or should not be applied to this particular fact setting.
Interestingly, the Deputy Solicitor General also represented the United States government and emphasized the importance of the protection offered by the doctrine of equivalents. He indicated that the Judge should decide the ultimate question of infr ingement under the doctrine of equivalents because resolving the question inherently requires interpreting the scope of claims, an issue reserved for judges according to the Court's recent decision in Markman. The jury's power should therefore be limited to resolving factually disputed questions. Responding to Justice Ginsburg's question regarding the U.S. government's position urging its trading partners to adopt a doctrine of equivalents, the Deputy Solicitor General indicated that partners sho uld adopt something similar to the U.S. doctrine but not necessarily a one-to-one correspondence.
Although it is difficult to predict the Supreme Court's ruling, it seems unlikely the Court will set aside the "insubstantial difference" test originated by it and later restated by the Federal Circuit en bank majority. The Court's interests appear to center on the judge/jury role in applying the doctrine of equivalents. Since a decision is expected to be handed down sometime in December or next January, patent professionals around the world eagerly await the outcome to see how the Court will resol ve these issues relating to the doctrine of equivalents.
Test for Equivalency
Despite the unsettled fate of Hilton Davis, the Federal Circuit has developed a substantial amount of case law on the doctrine of equivalents over the more than one year since deciding Hilton Davis. Regarding the objective factors to d etermine insubstantial difference, recent cases indicate that the court's analysis is focusing on factors such as the distinction between copying and designing around, and one skilled in the art's knowledge of interchangeability bet ween the disputed element in the patentee's claims and the modified element adopted by the defendant, (i.e. factors that the Hilton Davis majority emphasized).
Since these factors closely parallel those used in deciding nonobviousness, the Federal Circuit has continuously confronted the difficult question of whether a separate patent on the accused device can establish substantial difference and prevent a f inding of infringement under the doctrine of equivalents. The same question plagued German judges and patent professionals when the German Supreme Court affirmed a test for infringement under the doctrine of equivalents similar to the "insubstantial test " in Hilton Davis. Although a more recent German Supreme Court decision clarified the relationship by making the test for nonobviousness (inventive step) and the test for infringement under the doctrine of equivalents identi cal, the decision generated significant criticism by those concerned that it would result in insufficient protection of earlier patented inventions.
In contrast, since its own precedent clearly indicates that a patented product or process may infringe on an earlier patent, the Federal Circuit avoids giving a clear cut answer. It simply states that a separate patent is rele vant to the determination of insubstantial difference, but does not automatically avoid infringement. Only Judge Nies was of the viewpoint that the same test should be used for nonobviousness and infringement under the doctrine of equivalents.
Further confusion is introduced by the discrepancy among the Federal Circuit panels' views regarding whether the evidence used to establish the doctrine of equivalents should be presented on a limitation-by-limitation basis. The debate concerning wh ether infringement under the doctrine of equivalents should be analyzed on an element-by-element basis, or on the invention "as a whole," began with the Federal Circuit's Pennwalt decision. Pennwalt analyzed the claim ed invention and accused device on an element-by-element basis and denied infringement under the doctrine of equivalents, without even mentioning a prior decision which required the claimed invention and accused device be analyzed as a whole. In a more recent decision, the court ended the debate by denying one-to-one correspondence between the elements of claimed invention and the accused device. Because the major benefit of the element-by-element analysis i s to give courts a framework to evaluate elements on one-to-one correspondence basis, removal of such a framework renders the element-by-element analysis meaningless. Thus, the Federal Court has ceased to impose such a requirement in recent cases, and th e debate has become moot.
Since Hilton Davis did not address this issue and the "insubstantial difference" test suggests an "as a whole" approach rather than an "element-by-element" approach, the Federal Circuit's decisions after Hilton Davis are sharply split a s to whether the patentee should present evidence of equivalency with particularized testimony and liking arguments on a limitation-by-limitation basis. In National Presto Industries, Inc., Judge Newman did not clearly rejec t the defendant's argument that the patentee's evidence of equivalency was directed only to the substantial identity on "overall" function, way and result between the disputed elements of the claimed device and defendant's device. This suggests that evide nce presented should be directed at the overall identity of the three part test, and the claimed invention and accused device should be analyzed as a whole.
However, in Texas Instruments, Inc. v. Cypress Semiconductor Corp.,  after finding no literal infringement, Judge Laurie, one member of the panel which decided National Presto, was not persuaded by TI's argument t hat the defendant's device which used a "die pad," infringed upon the patented claims under the doctrine of equivalents. TI's argument primarily relied on expert testimony on the overall identity of the function/way/result between the defendant device an d the patented invention. Agreeing with the district court, Judge Laurie emphasized the requirement of presenting evidence with particularized testimony and liking argument on a limitation-by-limitation basis. Citing Pennwalt, as well as a case d ecided after Hilton Davis following Pennwalt, the court denied to read National Presto to say that Hilton Davis overruled its own precedent which requires equivalency on a limitation-by-limitation basis. The return of the element-by-element analysis also revived the fourth "why" prong, which was proposed to be added to the three part test to assist juries in reaching a reasonable conclusion when determining infringement under the doctrine of equivalents.< A HREF="#q26">
The restrictive view on infringement under the doctrine of equivalents indicated by some recent decisions may result in insufficient rewards for inventors. As previously discussed, to find literal infringement on the accused device which is not expl icitly disclosed in the specification becomes more difficult after Markman. Now, a defendant's insubstantial modification which is obvious to one skilled in the art and implicitly disclosed by the specification will likely be analyzed and found to infringe under the doctrine of equivalents. As some panel decisions indicate, if the courts also adopt a restrictive view on infringement under the doctrine of equivalents, insubstantial modification which avoids the claim form adopted by the patentee m ay readily avoid infringement.
The Federal Circuit repeatedly emphasized in cases dealing with nonobviousness that claimed inventions and the subject matter of the prior art must be analyzed as a whole. Analysis of a claimed invention should not vary depending on whether its subj ect matter is compared with respect to its patentability or infringement. Graver Tank & MFG Co. v. Linde Air Products Co., also clearly indicates that the function and result identity of the substituted ingredients is used to determine whether the substitution affects the overall result of the invention, which relates to the principle or object of the invention. Therefore, the Court emphasized the importance of identifying the purpose or use of the substituted ingredient i ncluded in the patented flux. The reason for examining the function/result identity is to determine the ultimate question of whether one skilled in the art would have known the interchageability of substituted ingredients. This analytical process closel y parallels the Court's inquiry in Graham v. John Deere Co., and thus provides support for the argument that the same analytical approach should be used in determining both nonobviousness and infringement under the doctrine o f equivalents.
Prosecution History Estoppel
The Hilton Davis majority significantly limited the application of prosecution history estoppel, noting that estoppel applies only to the extent necessary to maintain the patentability of the claimed invention. A change of claim scope during the prosecution does not automatically give rise to estoppel. In determining whether to apply estoppel, courts must look at the nature and purpose of the change. Since these factors are often difficult to establish, and courts re quire a showing that the change is substantial to overcome the prior art, a more effective approach to limiting infringement under the doctrine of equivalents is to rely on the prior art. This approach is elaborately discussed by J udge Rich in Wilson Sporting Goods Co. v. David Geoffrey & Assoc.
In General Am. Transp. Corp. v. Cryo-Trans, Inc., the defendant successfully established that the district court's finding of infringement under the doctrine of equivalents was clearly erroneous by arguing that the accus ed rail car is obvious from the prior art. Because this doctrine to limit the range of equivalency by the prior art enjoys the benefit of a rich body of case law regarding nonobviousness and predictability, defendants will likely rely on this doctrine, i nstead of the prosecution history estoppel.
Remaining unclear however, is the placement of the burden of proof required to show patentability over the prior art. Although Judge Rich in dicta clearly stated that this burden should be placed on the patentee, Judge Newman in National Presto Indus. v. West Bend Co., suggested that it be on the defendant.  The question of which party bears the burden of proof turns on the approach to the doctrine of equivalents. If the court regards protection against infringement under the doctrine of equivalents as additional to the normal pro tection, it will require that the patentee, rather than the defendant, bear the burden. In contrast, if the court regards such protection as essential and part of the normal protection, the patentee will have met its burden of proof when she establishes prima facie infringement by showing insubstantial difference. The burden is then on the defendant to overcome the equivalency with evidence to indicate that the accused device is part of the prior art or obvious from the prior art. By holding tha t courts must always examine infringement under the doctrine of equivalents after a finding of no literal infringement, the Hilton Davis majority made it clear that protection from infringement under the doctrine of equivalents is part of the norma l protection. This has been confirmed by a shift in the Federal Circuit's view on the burden of proof with respect to the prior art limitation.
- Toshiko Takenaka
 90 F.3d 1576, 39 U.S.P.Q.2d 1573 (Fed.Cir. 1996).
 384 F.2d 391, 155 U.S.P.Q. 697 (Ct. Cl. 1967).
 BNA's Patent Trademark & Copyright Journal (1301) 10 (Nov. 7, 1996).
 90 F.3d 1558, 39 U.S.P.Q.2d 1492 (Fed. Cir. 1995).
 78 F.3d 1575, 38 U.S.P.Q.2d 1126 (Fed. Cir. 1996). Also see, Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 39 U.S.P.Q.2d 1573 (Fed. Cir. 1996).
 Hoechst should be read to indicate the Federal Circuit's attitude toward interpreting claims consistent with the specification, but not to include all disclosed embodiments. When some embodiments are obviously not covered by claims a nd left for the public, the court does not allow inventors to recapture those unclaimed embodiments. E.g. Maxwell v. J. Baker, Inc., 86 F.3d 1098, 39 U.S.P.Q.2d (BNA) 1001 (Fed. Cir. 1996).
 A summary of the hearing is reported in BNA Patent, Trademark & Copyright Law Dayly, Oct. 17, 1996.
 62 F.3d 1512, 35 U.S.P.Q.2d 1641 (Fed. Cir. 1995).
 For further discussion of the doctrine of equivalents, see Toshiko Takenaka, Doctrine of Equivalents After Hilton Davis: A Comparative Law Analysis, 22 Rutgers Computer and Technology Law Journal 479 (1996).
 For a detailed discussion of German patent claim interpretation, see Toshiko Takenaka, Interpreting Patent Claims: The United States, Germany and Japan, 17 IIC Studies (1995).
 52 BNA's Patent, Trademark and Copyright Jounal (1298) 673 (Oct. 17, 1996)
 Roton Barrier, Inc. v. Stanley Works, 79 F.3d 1112, 37 U.S.P.Q.2d 1816 (Fed. Cir. 1996); Zygo Corp. v. Wyko Corp., 79 F.3d 1563, 38 U.S.P.Q.2d 1281 (Fed. Cir. 1996).
 Litton Sys. v. Honeywell, Inc., 87 F.3d 1559, 39 U.S.P.Q.2d (BNA) 1321 (Fed. Cir. 1996).
 Jochen Pagenberg, More Refined Rules of Claim Interpretation in Germany--Are They Necessary?, 26 IIC 228 (1995).
 "Segmentation Device for Tree Tunks" (Zerlegvorrichtung fuerBaumstaemme), 26 IIC 261 (1995)(BGH 1994).
 Atlas Powder Co. v. E. I. Du Pont de Nemours & Co., 750 F.2d 1569, 224 U.S.P.Q. 409 (Fed. Cir. 1984).
 SchlbkZygo Corp. v. Wyko Corp., 79 F.3d 1563, 38 U.S.P.Q.2d 1281 (Fed. Cir. 1996)(stating that the nonobviousness of the accused device, evidenced by the grant of a United States patent, is relevant to the issue of whether the chang e therein is substantial).
 National Presto Indus. v. West Bend Co., 76 F.3d 1185, 37 U.S.P.Q.2d 1685 (Fed. Cir. 1996)(noting that the grant of a separate patent on the accused device does not automatically avoid infringement, either literal or by equivalency) ; Hoechst Celanese Corp. v. BP Chems. Ltd., 78 F.3d 1575, 38 U.S.P.Q.2d (BNA) 1126 (Fed. Cir. 1996)(recognizing that the fact of separate patentability presents no legal or evidentiary presumption of noninfringement).
 Roton Barrier, Inc. v. Stanley Works, 79 F.3d 1112, 37 U.S.P.Q.2d 1816 (Fed. Cir. 1996)("A substitution in a patented invention cannot be both nonobvious and insubstantial. I would apply nonobviousness as the test for the 'insubsta ntial change' requirement of Hilton Davis.").
 Pennwalt Corp. v. Durand-Wayland, Inc., 833 F.2d 931, 4 U.S.P.Q.2d 1737 (Fed. Cir. 1987).
 Hughes Aircraft Co. v. United States, 717 F.2d 1351, 219 U.S.P.Q. 473 (Fed. Cir. 1983).
 Corning Glass Works v. Sumitomo Electric U.S.A., Inc., 868 F.2d 1251, 9 U.S.P.Q.2d 1962 (Fed. Cir. 1989).
 Supra note 18, 76 F.3d 1185.
 Supra note 4, 90 F.3d 1558.
 Athletic Alternatives, Inc. v. Prince Mfg., Inc., 73 F.3d 1573, 37 U.S.P.Q.2d 1365 (Fed. Cir. 1996).
 Malta v. Schulmerich Carillons, Inc., 952 F.2d 1320, 21 U.S.P.Q.2d (BNA) 1161 (Fed. Cir. 1991).
 Graver Tank & MFG Co. v. Linde Air Products Co., 339 U.S. 605 (1950).
 Graham v. John Deere Co., 383 U.S. 1, 148 U.S.P.Q. 459 (1966).
 Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 72 F.3d 857, 37 U.S.P.Q.2d (BNA) 1161, (Fed. Cir. 1995); Athletic Alternatives v. Prince Mfg., 73 F.3d 1573, 37 U.S.P.Q.2d 1365 (Fed. Cir. 1996).
 Pall Corp. v. Micron Separations, 66 F.3d 1211, 36 U.S.P.Q.2d 1225 (Fed. Cir. 1995).
 904 F.2d 677, 14 U.S.P.Q.2d 1942 (Fed. Cir. 1990).
 93 F.3d 766, 1996, 39 U.S.P.Q.2d 1801 (Fed. Cir. 1996).
 Supra note 31, 904 F.2d 677, 685.
 Supra note 18, 76 F.3d 1185, 1192.
 For further discussion, see supra note 10.