The Doctrine of Equivalents Fails to Save Patent Infringement Suit: Ethicon Endo-Surgery, Inc., et al, v. Covidien LP

Following a bench trial, the District Court of Massachusetts held that Ethicon’s “shepherd’s hook” design for finger actuation of a forceps is not equivalent to a “finger loop” claimed by Covidien’s patent no. 9,241,759, and thus Covidien had failed to establish infringement for Ethicon’s Enseal X1 Large Jaw vessel sealer. Ethicon Endo-Surgery, Inc. v. Covidien LP, No. 16-12556-LTS (D. Mass., April 24, 2020.) The court provided an interesting analysis under the Doctrine of Equivalents.

Background

Ethicon sued Covidien for a declaration that Ethicon’s Enseal X1 Large Jaw vessel sealer does not infringe Covidien patent nos. 9,241,759 and 8,323,310. Covidien counterclaimed for infringement. This article focuses on Covidien’s assertion that Ethicon’s “shepherd’s hook” design for actuating the Enseal X1 device infringes on Covidien’s claimed “finger loop,” based on the Doctrine of Equivalents.

Claim 1 of the ‘759 patent is representative and recites in relevant part:

1. An endoscopic bipolar forceps, comprising:

               . . .

               a movable handle of unitary construction having a finger loop positioned towards a first end thereof, a drive flange positioned towards a second end thereof, and a locking flange disposed between the finger loop and the drive flange, the driver flange operably coupled to the drive sleeve towards the proximal end of the drive sleeve such that movement of the movable handle from an open position to a closed position moves the movable jaw member relative to the fixed jaw member from the first position to the second position;

               . . .

Example Finger Loop

Example Shepherd's Hook

Analysis

“[A] product or process that does not literally infringe upon the express terms of a patent claim may nonetheless be found to infringe if there is ‘equivalence’ between the elements of the accused product or process and the claimed elements of the patented invention.” Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 21 (1997).

The specification of the ‘759 patent states that claimed “finger loop” consists of a closed curved structure that surrounds the back and front of the inserted fingers, enabling the user to pull the movable handle to close the jaws of the device and to push the handle to open the jaws. ‘759 patent at 23:22-31. Covidien concedes that the shepherd’s hook design of the Enseal X1 device does not literally practice the finger loop limitation, but practices the limitation under the doctrine of equivalents. Under this doctrine, “[a]n element in the accused product is equivalent to a claim limitation if the differences between the two are ‘insubstantial’ to one of ordinary skill in the art.” Catalina Mktg. Int’l, Inc. v. Coolsavings.com, Inc., 289, F.3d 801, 812 (Fed. Cir. 2002)).

The Federal circuit applies two articulations of the test for equivalence. Under the insubstantial differences test, ‘[a]n element in the accused device is equivalent to a claim limitation if the only differences between the two are insubstantial.’” Honeywell Int’l Inc. v. Hamilton Sundstrand Corp., 370 F.3d 1131, 1139 (Fe. Cir 2004)). Alternatively, “[t]he function-way-result test provides that ‘an element in the accused device is equivalent to a claim limitation if it performs substantially the same function in substantially the same way to obtain substantially the same result.’’’ Voda v. Cordis Corp., 536 F.3d 1311, 1326 (Fed. Cir. 2016.

Covidien failed to show that Ethicon’s shepherd’s hook practices the finger loop limitation under either test. The Court observed the following differences between the finger loop and the shepherd’s hook.

  1. The finger loop handle is grasped by inserting one or more fingers into the opening of the closed loop. The handle with the shepherd’s hook design is grasped by holding on to the non-movable part of the handle and sliding one or more fingers against the curved, distal part of the handle from below or the side.
  2. Because the finger loop is closed, the finger loop receives the fingers, and the user must pull her fingers out of the finger loop when extricating her hand from the handle. To remove her fingers from the handle with the shepherd’s hook design, the user simply slips her fingers out of or away from the hook.
  3. The finger loop can contain the user’s fingers when the handle is held in every direction – right side up or upside down, and backwards – or forwards facing. The shepherd’s hook does not hold the fingers in place.
  4. The finger loop allows the user to use all her fingers in the loop to push the handle forward. In contrast, the shepherd’s hook design allows only for some of the fingers-those fitting behind the hook- to push the handle forward.

For these reasons, the Court concluded that the shepherd’s hook design does not perform substantially the same function, in substantially the same way, with substantially the same result as the finger loop, and further that the shepherd’s hook is not insubstantially different from the finger loop design. That two different designs may both enable a user to push and pull the handle to open and close the jaws of the forceps does not mean they are equivalent for purposes of infringement.

Lessons for Practice

Expect the doctrine of equivalents to be construed narrowly. An element must do more than perform the same function as a claim limitation to infringe under the doctrine of equivalents. How the element performs the function matters. The standard is either that the differences are “insubstantial,” or, perhaps more illuminating, that the element performs “substantially the same function in substantially the same way to obtain substantially the same result,” as the claim limitation.

 Also, keep this in mind when drafting claims. In this case, could the finger loop have been claimed more broadly as a “jaw control element?” By specifying a closed loop, was the limitation over specified?