Inventor's prior art patents and prosecution history lead to reversal of claim construction

October 26, 2010
Post by Blog Staff

In a recent decision, the Federal Circuit reversed a district court's grant of summary judgment of noninfringement and invalidity based on inadequate written description. The issue of infringement was reversed based on the district court's incorrect construction of a critical claim limitation. While the court held it was a "close case," it held the patentee had not acted as his own lexicographer and the specification and file history showed a broader construction was appropriate. In addition, a broader construction was supported by usage of the term in prior art patents by the same inventor.

On the written description issue, the court held there was at least a factual issue as to whether limitation at issue, which permitted reinforcement of any portion of a portion of the claimed product, was inadequately described. The court observed that the allegedly limiting language was a "preferred aspect" of the invention, and thus the patentee's experts' testimony that one in the art would interpret the specification as more broadly disclosing the device was sufficient to generate a fact issue. The district court characterized this testimony as "not helpful" when granting summary judgment of invalidity.

More detail of Laryngeal Mask Co. v. Ambu A/S after the jump.

Laryngeal Mask (LM) sued Ambu A/S for infringement of U.S. Patent 7,156,100 relating to a laryngeal mask airway device. LM's patent is directed to an artificial airway device used to deliver anesthetic gases during surgery and to establish unobstructed airways in patients in emergency situations. One problem with prior art laryngeals masks is that during insertion, the leading edge of the deflated cuff may fold over on itself, so that the rigid end of the mask catches the inside of the patient's throat. The '100 patent minimizes this risk by adding a reinforcing rib to stiffen the leading edge during insertion. An example of the disclosed mask is shown below:

Figure 2

Claim 1 of the patent was the only independent claim at issue and formed the basis for the district court's summary judgment. That claim is reproduced below with the relevant terms emphasized.
1. A laryngeal-mask airway device comprising: a backplate defining a passage; an inflatable cuff, the cuff defining a distal region and a central opening at least when inflated, the cuff being attached to the backplate, the cuff being insertable through a mouth of a patient to an inserted location within the patient, an airway extending from a laryngeal inlet of the patient, through the central opening, to the passage when the cuff is inflated and at the inserted location, at least a portion of the posterior portion of a wall of the cuff in the distal region being thicker and stiffer than other portions of the cuff.
The district court construed the claim term "backplate" as meaning a relatively rigid mask structure surrounded by the cuff and including a tube joint. The tube joint (92 in the figure above) is the connection between the mask and the airway tube. Based on this construction, the district court granted summary judgment that Ambu's accused devices do not infringe, because the accused devices lack a tube joint. Instead, in the accused devices the mask and airway tube are integrally molded as one continuous piece, rather than two pieces joined by a tube joint.

The district court construed the "thicker and stiffer" limitation as to not require the thicker and stiffer portion to be connected to the backplate. Based on this construction, the district court granted Ambu's motion for summary judgment of invalidity for lack of written description, holding the specification failed to describe a mask having a portion of the wall of the cuff being thicker and stiffer than other portions of the cuff that was not attached to the backplate. The district court disregarded LM's expert testimony to the contrary, finding it "not helpful." LM appealed.

The Federal Circuit reversed. With regard to the backplate limitation, LM argued that the district court improperly read a tube joint limitation into the limitation and that the claims are broad enough to include a mask integrally molded to the airway. During prosecution, LM deleted separate airway tube and tube joint language from the claims. Ambu asserted that every figure, every embodiment, and every description of the backplate in the '100 patent shows the backplate as a separate structure from the airway tube and including a tube joint for connection to the airway tube, and therefore the district court properly limited the claim to backplates with tube joints.

The Federal Circuit admitted this was a difficult case of claim construction. The preferred embodiment stated the backplate included a tube joint. However, in light of the claim language, specification, and prosecution history, the court concluded the claimed "backplate" did not require a tube joint. The court noted the specification has only one reference to a tube joint being part of the backplate, and that single sentence is not sufficient to require every backplate to include a tube joint. The court agreed with LM that the description is broad enough to include integrally molded devices as well as devices with a tube joint. Further, the court noted the amendment to remove the tube joint as a separate limitation during prosecution. In addition, the court noted there were two prior art patents related to laryngeal mask devices by the same inventor, and both disclosed backplates without tube joints. As a result, the Federal Circuit reversed the district court's construction of "backplate." Because of the district court's summary judgment of noninfringement was based on this erroneous claim construction, the Federal Circuit vacated that judgment and remanded for further proceedings.

Turning to the written description issue, LM agreed the specification did not describe an embodiment with the reinforced cuff region disconnected from the backplate, but asserted that such connection was not required by the specification. LM also presented testimony of two experts that one of ordinary skill in the art would read the specification to describe a thicker and stiffer cuff portion disconnected from the backplane.

The Federal Circuit agreed with LM that one of ordinary skill in the art could read the specification as providing for a thickened cuff that need not be connected to the backplate. Since this raised a genuine issue of material fact, summary judgment was reversed and the case remanded for further proceedings.

To read the full opinion in Laryngeal Mask Co. v. Ambu A/S, click here .

Post Categories

Comments (0)
Post a Comment

Captcha Image
Return to the Filewrapper Blog

Search Posts


The attorneys of McKee, Voorhees & Sease, P.L.C. designed this blog as an informational and educational resource about intellectual property law for our clients, other attorneys, and the public as a whole. Our goal is to provide cutting-edge information about recent developments in intellectual property law, including relevant case law updates, proposed legislation, and intellectual property law in the news.


McKee, Voorhees & Sease, P.L.C. provides this blog for general informational purposes only. By using this blog, you agree that the information on this blog does not constitute legal or other professional advice and no attorney-client or other relationship is created between you and McKee, Voorhees & Sease, P.L.C. Do not consider this blog to be a substitute for obtaining legal advice from a qualified, licensed attorney. While we try to revise this blog on a regular basis, it may not reflect the most current legal developments. We consciously refrain from expressing opinions on this blog and instead, offer it as a form of information and education, however if there appears an expression of opinion, realize that those views are indicative of the individual and not of the firm as a whole.

Sign Up For Our Newsletter

Enter your name and email address to receive the latest news and updates from us and our attorneys.

Subscribe to: MVS Newsletter

Subscribe to: Filewrapper® Blog Updates

  I have read and agree to the terms and conditions of McKee, Vorhees & Sease, P.L.C.