Narrowing Amendment and Prosecution History Estoppel

Felix v. American Honda (Fed. Cir. 2009)

Mr. Felix sued Honda for infringement of his patent covering a truck bed with a storage compartment underneath the bed. The Honda Ridgeline advertises a “lockable In-Bed Trunk®” that appears to serve the same overall purpose. The problem is that Felix’s asserted claim is rather narrow and the district court found no literal infringement and no infringement under the doctrine of equivalents. Asserted claim 6 reads as follows:

6. In combination with a vehicle including a vehicle bed, the improvement of a storage system which includes: a) an opening formed in the vehicle bed and including an opening rim; b) a compartment with an interior; c) said compartment being mounted on said bed with said compartment interior accessible through said opening; d) a lid assembly including lid mounting means for mounting said lid in covering relation with respect to said opening; e) a channel formed at the rim of said bed opening and including an inner flange; f) a weathertight gasket mounted on said flange and engaging said lid in its closed position; and g) a plurality of drain holes formed in said channel.

In particular, the accused Honda truck bed has a “weathertight gasket” mounted on the lid rather than to the flange as claimed in the Felix patent.

On appeal, the Federal Circuit affirmed the lower court’s judgment of non-infringement – finding Honda did not literally infringe and that Felix’s claim under the doctrine of equivalents (DOE) was foreclosed by prosecution history estoppel. Here, I will discuss the DOE dispute.

Doctrine of Equivalents: The patent claims spell out the boundaries of an inventor’s claimed invention. However, courts may extend the scope of exclusionary rights beyond the literal claim language to capture equivalent products. In recent years, the doctrine of equivalents has been limited. This case, the doctrine of prosecution history estoppel came into play because Felix had narrowed his claims prosecution. (Actually, the applicant cancelled the broad independent claims and re-wrote the dependent claims into independent form. Under Honeywell, that process has the same estoppel effect as narrowing the independent claim.)

Tangential: The presumption of estoppel can be overcome with evidence that the reason for the narrowing amendment is no more than tangentially related to the equivalent in question. The evidentiary standard for proving the “no more than tangential relationship” is quite high. Here, Felix offered a credible alternative explanation, but the Federal Circuit rejected his argument because (1) he did not prove that his alternative was “the only reason” for the amendment and (2) he did not “explain the entire amendment.”

“Because we conclude that Felix is barred by the doctrine of prosecution history estoppel from relying on the doctrine of equivalents to prove that the accused In-Bed Trunk meets the gasket limitation, we also affirm the district court’s summary judgment of no infringement by equivalents.”

Drafting Strategies: One interesting aspect of this case is that Felix had to go through a couple of rounds of amendments. After first amending to add the gasket, Felix then had to amend again to secure allowance. Although the first amendment did not directly lead to allowance, the narrowing amendment still created a presumption of estoppel:

“The fact that the first amendment did not succeed and that a further amendment was required to place the claim in allowable form, however, is of no consequence as to the estoppel. It is the patentee’s response to a rejection—not the examiner’s ultimate allowance of a claim—that gives rise to prosecution history estoppel.

We therefore hold that the presumption of prosecution history estoppel attaches when a patentee cancels an independent claim and rewrites a dependent claim in independent form for reasons related to patentability, even if the amendment alone does not succeed in placing the claim in condition for allowance.”

Judge Linn also pointed to an “open question” in footnote 4:

“We leave open the question of whether the presumption of surrender would have attached as to the gasket limitation if, in response to the first office action, Felix had cancelled both claim 1 and claim 7, and had rewritten claim 8 in independent form, instead of attempting to secure the broader coverage of rewritten claim 7 as an intermediate step.”

[Corrected 3:40 CST]


Prison: The last stand for land line phones.

TIP Systems v. Phillips & Brooks (PBG) (Fed. Cir. 2008)

“This is a patent infringement case pertaining to wall-mounted telephones designed for use by prison inmates.”  Both the accused device and the patents focus on a telephone system that operates without the dangers of a phone cord. However, the TIP patents require a “handset” mounted in the wall of the phone box with a mouthpiece that “extends through” the wall.  These claims are exemplified in the figures.

The accused devices do not use a traditional handset, but rather use a separate ear-piece and mouthpiece. In addition, the accused device wall is flush – and the mouthpiece does not break through the wall.

Questionable claims of infringement are naturally resolved by a Markman hearing and subsequent summary judgment of noninfringement. Here, the district court found (i) that the claimed handset must include a handle with both an ear-piece and mouthpiece and (ii) that the mouthpiece must pass through an aperture in the front wall of the phone box.  It was clear that the accused device did not exhibit either of these features and thus could not infringe.

The definition of the handset was made easy because the claims stated that: “a telephone handset being a handle with an ear-piece at one end and a mouthpiece at an opposite end.” The exact definition is support from the figures is also provided in the specification.

The CAFC affirmed on claim construction then went on to consider whether the elements may still be covered under the doctrine of equivalents (DOE). 

If an element is not literally covered by a claim, the device may still be considered infringing if the accused element is equivalent to the claimed element. Thus, to infringe a patent, each claim element or its equivalent must be found in an accused device.

Whether equivalency exists may be determined based on the “insubstantial differences” test or based on the “triple identity” test, namely, whether the element of the accused device “performs substantially the same function in substantially the same way to obtain the same result.” 

The game in the doctrine of equivalents is defining an ‘element.’  The patentee wants a broad definition (the telephones as a whole are very similar) while the defendant argues for a narrow definition. Here, the defendants won when the courts found that a “handle” is an element of the claim.  Since the accused devices have no structure that is similar to a handle, they cannot infringe even as an equivalent.


Continued Vitiation of The Doctrine of Equivalents

Wleklinski (dba Comfort Strapp) v. Targus (Fed. Cir. 2007) (Non-Precedential).

PatentLawPic128In March, 2007, the Central District of California dismissed Comfort Strapp’s complaint on summary judgment — finding no proof of infringement.  Comfort Strapp’s patent relates to a comfortable shoulder strap for luggage.

The fight was over the construction of an “auxiliary strap means” limitation that requires the strap’s end sections be “made of a relatively non-stretchable material” and the strap’s center section be “made of [stretchable] material.”  Because the Targus auxiliary strap was made of a single material, the CAFC agreed that it could not literally infringe.

Doctrine of Equivalents: Accused products that exhibit only ‘insubstantial differences’ from the claimed patent may also be considered infringing under the doctrine of equivalents. (DOE). However, the DOE cannot apply where it would vitiate a claim limitation.

Here, the Federal Circuit panel agreed that as a matter of law, the doctrine of equivalents does not allow a claimed two-material strap to encompass a strap made of only one material. According to the appellate panel, such a reading would be “the fundamental opposite of the claimed invention.” Citing Freedman Seating.

Notes: Although the court’s trend to limit the doctrine of equivalents began well before the Supreme Court’s KSR ruling. The bulked-up nonobviousness test naturally reduces the scope of the doctrine of equivalents as the DOE cannot extend to cover variations that would have been obvious at the time of patenting.

CAFC Reaffirms that Doctrine of Equivalents Applies to Ranges

US Philips v. Iwasaki (Fed. Cir. 2007)

Philips sued Iwasaki for infringement of its patents covering mercury-tungsten halogen light. The district court awarded summary judgment of non-infringement to Iwasaki.

Vitiation and the Doctrine of Equivalents: The asserted patent claims a target concentration of 1.6 ± 0.4 × 10-4 µmol/mm3. Based on that claim language, the district court ruled that the claim was “intended to establish the demarcation of boundaries [with] the type of precision that is closely analogous to the metes and bounds of a deed of real property.”  Thus, according to the court, allowing the claim to cover any concentration outside of the clearly claimed limits would vitiate the limitation.

On appeal, the CAFC rejected the notion that an expanded numerical range would vitiate the claim language.

“A reasonable juror could make a finding that a quantity of halogen outside that range is insubstantially different from a quantity within that range without “ignore[ing] a material limitation” of the patent claim.”

This decision conforms to prior decisions that allow equivalents for numerical ranges, but not for other limits (such as a claimed “majority.” Moore).

Notice of Infringement: 35 U.S.C. § 287(a) provides that damages for patent infringement only begin to accrue once the infringer was “notified of the infringement.” (Marking constitutes constructive notice). Notice requires a charge of infringement directed to a specific product, device, or action. The notice must also normally include the patentee’s identity. Here, the infringement letter (sent by “Mr. Rolfes”) did not specifically indicate that Philips was the assignee, but the court found notice sufficient because (1) Philips was correctly listed as the assignee of the patent and (2) Philips had granted the sending party the “responsibility for licensing and enforcing” the patent. Thus, Philips may collect damages from the date of receipt of the letter.


  • Rounding in Claim Construction: “‘1.0’ may be said to have more significant digits than ‘1’ with no decimal point. Because [the claimed] ‘10-6’ and ‘10-4’ are simply the numbers 0.000001 and 0.0001 expressed as powers of ten, the claim language provides no basis for inferring any level of precision beyond the single digit ‘1.’ The way that power-of-ten quantities are used in the specification, discussed supra, confirms that the quantities of halogen described by the claims are not intended to be more precise.” — Why does this matter — Less precision means that the accused product may still literally infringe due to rounding.
  • Approximately: “[T]erms like ‘approximately’ serve only to expand the scope of literal infringement, not to enable application of the doctrine of equivalents.”

CAFC: Meaning of “About”

UltracetOrtho-McNeil Pharm. v. Caraco Pharm. (Fed. Cir. 2006).

Ortho’s patent covers a pain-relief combo of tramadol and acetaminophen with a ratio of “about 1:5.” Caraco’s drug has a ratio of 1:8.67.  The lower court construed the claims and found no infringement.

Claim Construction: On appeal, the Federal Circuit construed the term “about 1:5” by first looking at the intrinsic evidence.  In the patent and claims, Ortho had used the term “about” repeatedly: disclosed ratios included about 1:1, about 1:5, about 1:19 to about 1:5, and about 1:1600. 

The court reasoned that the term must have a narrow meaning in this patent because a broad meaning would leave other claimed ratios meaningless. The court also noted that the literal meaning of the term should be narrowly construed because Ortho “could have easily claimed a [broader] range of ratios”

An expert testified that the statistical range should be 1:3.6 to 1:7.1 based on a confidence interval constructed from the data in the patent, and the Federal Circuit agreed. (The patent discussed the importance of 95% CI).

Literal Infringement: The Federal Circuit found that there could be no literal infringement because the upper claimed bound for the ratio was 1:7.1 while Caraco’s ratio was 1:8.67.

Doctrine of Equivalents: No DOE because Ortho cancelled claims with broader range during reissue. Interestingly, the Court made this ruling based on vitiation rather than prosecution history estoppel:

[I]t cancelled the broader “comprising” claims, except for claim 6. In sum, having so distinctly claimed the “about 1:5” ratio, Ortho cannot now argue that the parameter is broad enough to encompass, through the doctrine of equivalents, ratios outside of the confidence intervals expressly identified in the patent. We agree with the district court that to do so would eviscerate the limitation.

Summary judgment of noninfringement affirmed