Tangential Equivalents: Recent Case Confirms There Is Life After Festo

On Oct. 4, 2004, the Federal Circuit rendered its opinion in Insituform Techs., Inc. v. Cat Contracting, Inc. (“Insituform IV“), 385 F.3d 1360 (Fed. Cir. 2004). This opinion is the first post-Festo Federal Circuit opinion that finds a successful rebuttal of the Festo presumption (eg, the presumption of the surrender of infringement under the doctrine of equivalents due to prosecution history estoppel) based on the “tangential relationship” prong of Festo. This case seems to set a fairly low bar for the rebuttal of the presumption. This is a significant development given the Federal Circuit's apparent desire to restrict the doctrine of equivalents (as reflected in its initial Festo ruling that was reversed by the Supreme Court, as well as by the tenor of the post-reversal Festo opinion).

The patent at issue in Insituform IV concerns a process for impregnating a pipe liner with resin. The process requires applying a vacuum to the inside of the liner using “a” vacuum cup attached to a vacuum source and connected to a hole cut in the outside of the liner near the resin. The resulting vacuum draws the resin into the liner. When the resin is drawn in up to the level of the vacuum cup, the cup is moved to another hole cut in the liner further along the length of the liner. The accused method differed from the claimed method only in that the accused method used multiple vacuum cups rather than “a” cup.

Following a bench trial (and several appeals), a judgment of infringement under the doctrine of equivalents was entered by the district court. The issue on appeal in Insituform IV was whether the doctrine of equivalents was barred by prosecution history estoppel, and in particular how the recent Festo decision affected this determination.

Prosecution history estoppel was applicable because the sole claim at issue, claim 1, was amended during prosecution to overcome a prior art patent. The amendment, among other things, added the limitations “a cup” and “the cup” from original claim 4. These limitations had previously been construed to mean a single vacuum cup. The district court entered judgment of infringement by equivalents against defendant's process that used multiple vacuum cups.

The issue on appeal was whether infringement by equivalents was permitted under Festo, given the amendment to the claim during prosecution. The Federal Circuit applied Festo and found that the amendment was a narrowing amendment and was made for substantial reasons related to patentability. Therefore, the Festo presumption of surrender of infringement by equivalents applied. This finding is consistent with the Federal Circuit's recent decision in Honeywell Int'l, Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1141 (Fed. Cir. 2004), holding that rewriting a dependent claim into independent form, coupled with cancellation of the original independent claim, creates a presumption of surrender of equivalents for the newly added limitations (ie, the limitations in the formerly dependent claim).

To rebut the presumption, the plaintiff argued that the reason for the amendment was to overcome a teaching in the prior art reference about the location of the vacuum source, namely that the vacuum source was applied at the far end of the liner, not near the resin. This remote location of the vacuum source in the prior art method caused a problem in that the method was ineffective when applied to a long length of liner, because it required an exceedingly powerful suction compressor in order to pull the resin into the liner. The plaintiff's patented process solved this problem by placing the vacuum source closer to the resin being pulled into the liner, thus allowing a less powerful suction compressor to be used. Therefore, according to plaintiff, the amendment was at most only tangentially related to the number of cups used. In contrast, the defendant pointed out that the original claim covered any number of cups while the claim, as amended, and interpreted covered only a single cup. Since the defendant's multiple cup process fell squarely within the territory surrendered by the amendment, defendant argued that its process could not be covered by the doctrine of equivalents.

The Federal Circuit held that the Festo presumption had been rebutted, and ruled for plaintiff. The court noted that the prior art disclosed the use of a single vacuum source, not multiple vacuum cups, and that the single vacuum source was located at the far end of the liner. The Federal Circuit also noted that plaintiff's amendment was made to distinguish over the location of the vacuum source in the prior art reference, not the number of vacuum cups, stating: “there is no indication in the prosecution history of any relationship between the narrowing amendment and a multiple cup process, which is the alleged equivalent.” On this basis, the court found that the plaintiff had successfully rebutted the Festo presumption by establishing that the amendment narrowing the claim to a single cup was only tangentially related to the multiple cup process used by the defendant, and affirmed the district court's judgment of infringement under the doctrine of equivalents.

Analysis and Implications

While few solid conclusions can be drawn from just one case, the Federal Circuit's reasoning in Insituform IV suggests that the doctrine of equivalents may have more life in it than many believed after Festo.

In Festo Corp. v. Shoketsu Kinzoku Kogyu Kabushiki Co., Ltd., 535 U.S. 722, 740-741 (2002), the Supreme Court held that a narrowing amendment creates a rebuttable presumption that the patentee surrendered all subject matter between the original and the narrowed claim language. The Court further held that the patentee can overcome this presumption by showing: 1) that the equivalent at issue was unforeseeable when the claim amendment was made; 2) that the amendment made bears only a tangential relationship to the equivalent, or 3) there was some other reason that the patentee could not reasonably be expected to have described the alleged equivalent.

On remand from the Supreme Court, the Federal Circuit held that the “tangential relation” prong could not be satisfied where an amendment was made to overcome prior art that included the equivalent that the patentee was seeking to cover under the doctrine of equivalents. This decision left open the question of what types of amendments would constitute a merely “tangential relation” to an alleged equivalent. See Festo Corp. v. Shoketsu Kinzoku Kogyu Kabushiki Co., Ltd., 344 F.3d 1359 (Fed. Cir. 2003).

As discussed above, in Insituform IV, the Federal Circuit held that where an amendment is made to overcome prior art which does not include the equivalent, and where the reason for the amendment is only tangentially related to the equivalent, the doctrine of equivalents survives to be asserted against the alleged equivalent. In addition, the reasoning in Insituform IV suggests a potentially broader survival of the doctrine of equivalents. If the reason for an amendment is to distinguish the claim over the prior art, and the equivalent is not disclosed in the prior art, then this reason in nearly all cases will have nothing to do with the equivalent. It will be the rare case indeed where the patentee's reason for narrowing its claim to overcome a prior art reference is to avoid an element not present in that reference.

Thus, for amendments that overcome prior art, it appears from the Federal Circuit's reasoning in Insituform IV that a patentee should be able to rebut the Festo presumption in most cases where the accused equivalent is not found in the prior art reference that caused the amendment. Since under pre-Festo law, amendments made to distinguish over prior art that did contain the alleged equivalent already resulted in surrender of the equivalent, most post-Festo amendments based on prior art should enjoy the same doctrine of equivalents scope they enjoyed prior to Festo, as long as the patentee provides reasons for the amendments. Two recent district court opinions adopt this broader application of Festo. See Cordis Corp. v. Medtronic AVE, Inc., 336 F.Supp. 2d 363 (D. Del. 2004); Engineered Products Co. v. Donaldson Co., Inc., 313 F.Supp. 2d 951 (N.D. Iowa 2004).

For amendments to overcome non-prior art rejections, such as section 112 rejections or double-patenting rejections, or voluntary amendments where there is no rejection to overcome, the analysis is more difficult because there is no prior art against which the alleged equivalent can be compared. In a recent case dealing with a voluntary amendment made to forestall an expected double-patenting rejection, the district court found that the presumption was rebutted where the patentee's reasons for amending its claims to distinguish over the claims of its own prior patent were only tangentially related to the alleged equivalent. See Amgen, Inc. v. Hoechst Marion Roussel, Inc., 287 F.Supp. 2d 126 (D. Mass. 2003).

In Amgen, the prior patent broadly claimed either a human or non-human form of a protein. The patentee's apparent reason for the narrowing amendment was to cover the human form of the protein only. However, the language of the claim recited a specific protein sequence depicted in one of the patent figures. This sequence contained 166 amino acids, and thus the claim was construed to be limited to a 166 amino acid sequence. Since the allegedly infringing sequence only had 165 amino acids, the district court found that there was no literal infringement. However, the district court found that the 165 amino acid sequence was an equivalent of the claimed 166 amino acid sequence.

The court found that the patentee's objectively apparent reason for the amendment, based on the prosecution history, was merely to claim the human form of the protein, and not to claim any specific amino acid sequence. This was supported by a finding that a 165 amino acid sequence was not in the prior art, and thus there was no need for plaintiff to distinguish its claim over a 165 amino acid sequence. Based on these findings, the court held that the amendment was only tangentially related to the equivalent containing 165 amino acids, and thus the Festo presumption was rebutted.

In Amgen, the district court's focus was on the patentee's reasons for distinguishing its claims over its own prior patent (which was not prior art), along with examining whether the patentee had to distinguish its claim over prior art containing the equivalent, even though the amendment was not triggered by a prior art rejection. For most section 112 rejections, however, as well as many voluntary amendments, there will be nothing specific to compare the equivalent to except the reasons given by the patentee for the amendment. The patentee's reasons will therefore be the primary, if not exclusive, focus of a reviewing court's analysis. If no reasons are given, then there will be nothing to compare the equivalent against, and the presumption of surrender will likely not be rebutted. Thus, it is critical for patent applicants to present viable reasons for any amendments made, if any scope of equivalents is to be preserved.

While it is too early to draw a definitive conclusion, Insituform IV seems to suggest that Festo is essentially an extension of Warner-Jenkinson, designed to require patentees to give reasons for their claim amendments. See Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). Warner-Jenkinson established that any unexplained claim amendments were presumptively made for patentability reasons, and therefore were subject to the pre-Festo flexible bar on doctrine of equivalents. Festo subsequently extended Warner-Jenkinson by establishing that unexplained claim amendments were not only presumptively made for patentability reasons, but were also presumptively entitled to no range of equivalents. Since the Festo analysis is limited to a review of the intrinsic record except under the foreseeability prong, the Festo presumption is unlikely to be rebuttable for unexplained amendments unless the equivalent was truly unforeseeable at the time of the amendment. For amendments with explanations in the prosecution history, however, Insituform IV suggests that the presumption should be rebuttable for most amendments that would not have triggered estoppel prior to Festo.

On Oct. 4, 2004, the Federal Circuit rendered its opinion in Insituform Techs., Inc. v. Cat Contracting, Inc. (“Insituform IV“), 385 F.3d 1360 (Fed. Cir. 2004). This opinion is the first post-Festo Federal Circuit opinion that finds a successful rebuttal of the Festo presumption (eg, the presumption of the surrender of infringement under the doctrine of equivalents due to prosecution history estoppel) based on the “tangential relationship” prong of Festo. This case seems to set a fairly low bar for the rebuttal of the presumption. This is a significant development given the Federal Circuit's apparent desire to restrict the doctrine of equivalents (as reflected in its initial Festo ruling that was reversed by the Supreme Court, as well as by the tenor of the post-reversal Festo opinion).

The patent at issue in Insituform IV concerns a process for impregnating a pipe liner with resin. The process requires applying a vacuum to the inside of the liner using “a” vacuum cup attached to a vacuum source and connected to a hole cut in the outside of the liner near the resin. The resulting vacuum draws the resin into the liner. When the resin is drawn in up to the level of the vacuum cup, the cup is moved to another hole cut in the liner further along the length of the liner. The accused method differed from the claimed method only in that the accused method used multiple vacuum cups rather than “a” cup.

Following a bench trial (and several appeals), a judgment of infringement under the doctrine of equivalents was entered by the district court. The issue on appeal in Insituform IV was whether the doctrine of equivalents was barred by prosecution history estoppel, and in particular how the recent Festo decision affected this determination.

Prosecution history estoppel was applicable because the sole claim at issue, claim 1, was amended during prosecution to overcome a prior art patent. The amendment, among other things, added the limitations “a cup” and “the cup” from original claim 4. These limitations had previously been construed to mean a single vacuum cup. The district court entered judgment of infringement by equivalents against defendant's process that used multiple vacuum cups.

The issue on appeal was whether infringement by equivalents was permitted under Festo, given the amendment to the claim during prosecution. The Federal Circuit applied Festo and found that the amendment was a narrowing amendment and was made for substantial reasons related to patentability. Therefore, the Festo presumption of surrender of infringement by equivalents applied. This finding is consistent with the Federal Circuit's recent decision in Honeywell Int'l, Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1141 (Fed. Cir. 2004), holding that rewriting a dependent claim into independent form, coupled with cancellation of the original independent claim, creates a presumption of surrender of equivalents for the newly added limitations (ie, the limitations in the formerly dependent claim).

To rebut the presumption, the plaintiff argued that the reason for the amendment was to overcome a teaching in the prior art reference about the location of the vacuum source, namely that the vacuum source was applied at the far end of the liner, not near the resin. This remote location of the vacuum source in the prior art method caused a problem in that the method was ineffective when applied to a long length of liner, because it required an exceedingly powerful suction compressor in order to pull the resin into the liner. The plaintiff's patented process solved this problem by placing the vacuum source closer to the resin being pulled into the liner, thus allowing a less powerful suction compressor to be used. Therefore, according to plaintiff, the amendment was at most only tangentially related to the number of cups used. In contrast, the defendant pointed out that the original claim covered any number of cups while the claim, as amended, and interpreted covered only a single cup. Since the defendant's multiple cup process fell squarely within the territory surrendered by the amendment, defendant argued that its process could not be covered by the doctrine of equivalents.

The Federal Circuit held that the Festo presumption had been rebutted, and ruled for plaintiff. The court noted that the prior art disclosed the use of a single vacuum source, not multiple vacuum cups, and that the single vacuum source was located at the far end of the liner. The Federal Circuit also noted that plaintiff's amendment was made to distinguish over the location of the vacuum source in the prior art reference, not the number of vacuum cups, stating: “there is no indication in the prosecution history of any relationship between the narrowing amendment and a multiple cup process, which is the alleged equivalent.” On this basis, the court found that the plaintiff had successfully rebutted the Festo presumption by establishing that the amendment narrowing the claim to a single cup was only tangentially related to the multiple cup process used by the defendant, and affirmed the district court's judgment of infringement under the doctrine of equivalents.

Analysis and Implications

While few solid conclusions can be drawn from just one case, the Federal Circuit's reasoning in Insituform IV suggests that the doctrine of equivalents may have more life in it than many believed after Festo.

In Festo Corp. v. Shoketsu Kinzoku Kogyu Kabushiki Co., Ltd., 535 U.S. 722, 740-741 (2002), the Supreme Court held that a narrowing amendment creates a rebuttable presumption that the patentee surrendered all subject matter between the original and the narrowed claim language. The Court further held that the patentee can overcome this presumption by showing: 1) that the equivalent at issue was unforeseeable when the claim amendment was made; 2) that the amendment made bears only a tangential relationship to the equivalent, or 3) there was some other reason that the patentee could not reasonably be expected to have described the alleged equivalent.

On remand from the Supreme Court, the Federal Circuit held that the “tangential relation” prong could not be satisfied where an amendment was made to overcome prior art that included the equivalent that the patentee was seeking to cover under the doctrine of equivalents. This decision left open the question of what types of amendments would constitute a merely “tangential relation” to an alleged equivalent. See Festo Corp. v. Shoketsu Kinzoku Kogyu Kabushiki Co., Ltd., 344 F.3d 1359 (Fed. Cir. 2003).

As discussed above, in Insituform IV, the Federal Circuit held that where an amendment is made to overcome prior art which does not include the equivalent, and where the reason for the amendment is only tangentially related to the equivalent, the doctrine of equivalents survives to be asserted against the alleged equivalent. In addition, the reasoning in Insituform IV suggests a potentially broader survival of the doctrine of equivalents. If the reason for an amendment is to distinguish the claim over the prior art, and the equivalent is not disclosed in the prior art, then this reason in nearly all cases will have nothing to do with the equivalent. It will be the rare case indeed where the patentee's reason for narrowing its claim to overcome a prior art reference is to avoid an element not present in that reference.

Thus, for amendments that overcome prior art, it appears from the Federal Circuit's reasoning in Insituform IV that a patentee should be able to rebut the Festo presumption in most cases where the accused equivalent is not found in the prior art reference that caused the amendment. Since under pre-Festo law, amendments made to distinguish over prior art that did contain the alleged equivalent already resulted in surrender of the equivalent, most post-Festo amendments based on prior art should enjoy the same doctrine of equivalents scope they enjoyed prior to Festo, as long as the patentee provides reasons for the amendments. Two recent district court opinions adopt this broader application of Festo. See Cordis Corp. v. Medtronic AVE, Inc., 336 F.Supp. 2d 363 (D. Del. 2004); Engineered Products Co. v. Donaldson Co., Inc., 313 F.Supp. 2d 951 (N.D. Iowa 2004).

For amendments to overcome non-prior art rejections, such as section 112 rejections or double-patenting rejections, or voluntary amendments where there is no rejection to overcome, the analysis is more difficult because there is no prior art against which the alleged equivalent can be compared. In a recent case dealing with a voluntary amendment made to forestall an expected double-patenting rejection, the district court found that the presumption was rebutted where the patentee's reasons for amending its claims to distinguish over the claims of its own prior patent were only tangentially related to the alleged equivalent. See Amgen, Inc. v. Hoechst Marion Roussel, Inc., 287 F.Supp. 2d 126 (D. Mass. 2003).

In Amgen, the prior patent broadly claimed either a human or non-human form of a protein. The patentee's apparent reason for the narrowing amendment was to cover the human form of the protein only. However, the language of the claim recited a specific protein sequence depicted in one of the patent figures. This sequence contained 166 amino acids, and thus the claim was construed to be limited to a 166 amino acid sequence. Since the allegedly infringing sequence only had 165 amino acids, the district court found that there was no literal infringement. However, the district court found that the 165 amino acid sequence was an equivalent of the claimed 166 amino acid sequence.

The court found that the patentee's objectively apparent reason for the amendment, based on the prosecution history, was merely to claim the human form of the protein, and not to claim any specific amino acid sequence. This was supported by a finding that a 165 amino acid sequence was not in the prior art, and thus there was no need for plaintiff to distinguish its claim over a 165 amino acid sequence. Based on these findings, the court held that the amendment was only tangentially related to the equivalent containing 165 amino acids, and thus the Festo presumption was rebutted.

In Amgen, the district court's focus was on the patentee's reasons for distinguishing its claims over its own prior patent (which was not prior art), along with examining whether the patentee had to distinguish its claim over prior art containing the equivalent, even though the amendment was not triggered by a prior art rejection. For most section 112 rejections, however, as well as many voluntary amendments, there will be nothing specific to compare the equivalent to except the reasons given by the patentee for the amendment. The patentee's reasons will therefore be the primary, if not exclusive, focus of a reviewing court's analysis. If no reasons are given, then there will be nothing to compare the equivalent against, and the presumption of surrender will likely not be rebutted. Thus, it is critical for patent applicants to present viable reasons for any amendments made, if any scope of equivalents is to be preserved.

While it is too early to draw a definitive conclusion, Insituform IV seems to suggest that Festo is essentially an extension of Warner-Jenkinson, designed to require patentees to give reasons for their claim amendments. See Warner-Jenkinson Co. v. Hilton Davis Chemical Co. , 520 U.S. 17 (1997). Warner-Jenkinson established that any unexplained claim amendments were presumptively made for patentability reasons, and therefore were subject to the pre-Festo flexible bar on doctrine of equivalents. Festo subsequently extended Warner-Jenkinson by establishing that unexplained claim amendments were not only presumptively made for patentability reasons, but were also presumptively entitled to no range of equivalents. Since the Festo analysis is limited to a review of the intrinsic record except under the foreseeability prong, the Festo presumption is unlikely to be rebuttable for unexplained amendments unless the equivalent was truly unforeseeable at the time of the amendment. For amendments with explanations in the prosecution history, however, Insituform IV suggests that the presumption should be rebuttable for most amendments that would not have triggered estoppel prior to Festo.