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Unambiguous Claims Do Not Cover Only Disclosed Embodiments Without a Clear and Unmistakable Disclaimer

03-1082
February 11, 2004

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Last Month at the Federal Circuit - March 2004

Judges: Bryson (author), Lourie, and Dyk

In Liebel-Flarsheim Co. v. Medrad, Inc., No. 03-1082 (Fed. Cir. Feb. 11, 2004), the Federal Circuit reversed the district court’s claim construction of four patents assigned to the Liebel- Flarsheim Company (“Liebel”), vacated a SJ that Medrad, Inc. (“Medrad”) did not infringe any of the asserted four patents, and remanded the case back to the district court for further proceedings.

The four patents at issue are directed to the use of powered fluid injectors, such as syringes, for injecting fluid into patients during medical procedures. Two of the patents, U.S. Patent Nos. 5,456,669 (“the ‘669 patent”) and 6,658,261 (“the ‘261 patent”), claim several methods and devices relating to front-loadable injectors. The specifications of the ‘669 and ‘261 patents are essentially identical, each describing a pressure jacket surrounding the syringe to prevent it from breaking under the internal pressure generated when fluid is injected into the patient. Despite that none of the asserted claims expressly refers to a pressure jacket, the district court construed the claims to require the use of a pressure jacket around the syringe. That construction was based primarily on the fact that the ‘669 and ‘261 patents do not contain any description of an injector that lacks a pressure jacket. After finding that the claim limitation “syringe receiving opening” was ambiguous as to the location of the opening, the court looked to the specification and concluded that, since each of the disclosed embodiments included an opening at the front end of a pressure jacket, the “opening” had to be located at the front end of a pressure jacket. Because Medrad’s accused devices did not use pressure jackets, the court granted SJ of noninfringement.

The other two patents, U.S. Patent Nos. 5,662,612 (“the ‘612 patent”) and 5,928,197 (“the ‘197 patent”) are drawn to methods and devices for controlling the plunger drives in such powered injectors. The specifications of the ‘612 and ‘197 patents also have a common specification, which addresses the problem of calibrating the amount of fluid to be injected into a patient based on the critical features of the particular syringe that is being used. The ‘612 and ‘197 patents solve this problem by using a detector to generate electrical signals based on “physical indicia” on the syringe and a control circuit for computing various syringe properties. The district court construed the claim language “physical indicia related to the amount of fluid in the syringe” and “control circuit” for computing “the amount of fluid in said syringe using said electrical signal” as requiring a direct relationship between the syringe properties in question and the “physical indicia” of the syringe. Since Medrad’s accused devices use a look-up table to identify syringe properties based on the type of electrical signals received from a detector, the district court granted SJ of noninfringement.

With respect to the ‘669 and ‘261 patents, Liebel appealed the district court’s claim construction, arguing that the intrinsic record did not limit the scope of the asserted claims to cover only injectors that include pressure jackets. Medrad argued that the ‘669 and ‘261 patents must be construed as limited to devices that have pressure jackets because, when the subject matter claimed in a patent is the only subject matter disclosed, that subject matter is the invention and not simply a preferred embodiment of a broader invention. Medrad also argued that if the asserted claims are not so construed, the validity of the ‘669 and ‘261 patents would be called into question.

The Federal Circuit rejected the district court’s claim construction. With respect to the term “opening,” the Court held that there was no reason to believe that this term was ambiguous. Since, in common usage, an opening is simply an aperture, the Court found no basis to read this term restrictively. The Court also recognized that none of the asserted claims actually state, explicitly or by necessary implication, that the opening must be formed in conjunction with a pressure jacket. And the Court emphasized that neither the specification nor the prosecution history demonstrate a clear and unmistakable intention to limit claim scope to an opening that is located at the front end of a pressure jacket. To the contrary, the Court noted that, by intentionally removing the pressure jacket claim limitation during prosecution and stating that there is not “necessarily a pressure jacket” in the claimed devices, Liebel evidenced a clear intention to claim methods and devices in which pressure jackets were not required. In addition, since the ‘669 and ‘261 patents both contain claims that explicitly recite the requirement of a pressure jacket, but are dependent upon asserted independent claims that do not contain such a requirement, the Court held that the doctrine of claim differentiation created a strong and unrebutted presumption that the independent claims are not so limited. Finally, the Court held that it was improper for the district court to limit the asserted claims simply because they might be vulnerable to separate validity challenges.

With regard to the ‘612 and ‘197 patents, Liebel and Medrad both appealed the district court’s claim construction. Liebel argued that the phrase “physical indicia related to the amount of fluid in the syringe” does not require a direct relationship. Medrad also appealed that claim construction, asserting that the district court adopted an improperly narrow claim construction because the ‘612 and ‘197 patents only describe the “physical indicia” as providing information as to the length of the extender.

The Federal Circuit held that the claim language did not support the district court’s claim construction. The Court found that the term “related to” by itself does not limit the relationship between “physical indicia” and the properties in question to a direct relationship. Similarly, the claim language “control circuit” for computing “the amount of fluid in said syringe using said electrical signal” does not suggest that the control circuit must use the electrical signal in any particular way. The Court also held that the prosecution history did not evidence a clear disavowal of claim scope since the applicants distinguished the prior art by arguing that it did not disclose any “physical indicia” at all.

Finally, the Federal Circuit rejected Medrad’s argument. The Court found that the claim language did not limit the “physical indicia” to indicia that must be related to the length of the extender. Instead, the dependent claims of the ‘612 and ‘197 patent called for physical indicia that are related to various properties, including the amount of fluid in the syringe, the distance of the plunger from the ends of the syringe, the distance to the end of the plunger’s travel position, and the range of travel of the ram, which drives the plunger within the syringe. According to the Court, the doctrine of claim differentiation suggests that Liebel demonstrated a clear intent to cover a syringe having virtually any kind of “physical indicia.” The Court also found that the prosecution history made it clear that Liebel intended that asserted claims cover syringes having “physical indicia” other than the length of the extender.