Limitations describing how an apparatus is made can structurally limit the apparatus

Andrew Melick | June 12, 2013

Regents of University of Minnesota v. AGA Medical Corp.

June 3, 2013

Panel:  Rader, Wallach, Dyk.  Opinion by Dyk.


Regents of University of Minnesota (“University”) sued AGA Medical for infringement of U.S. Patents 6,077,281 and 6,077,291 directed to medical devices called septal occluders.  A claim at issue recites two disks having central membranes, the two disks being “affixed” to each other at the central membranes “to define a conjoint disk.”  The accused product was a molded one-piece device.  In the district court, the claim was construed as to require that the disks, before being affixed, exist separately as individual disks that are then attached to each other.  Since the accused device was a single molded device and was not constructed from two separate disks, the district court entered summary judgment of non-infringement.  The CAFC affirmed this construction and the summary judgment of non-infringement.

Another claim at issue was found to be anticipated.  The University attempted to use prosecution disclaimer to narrow the claim and avoid anticipation.  However, the court rejected the prosecution disclaimer because the prosecution disclaimer was from a parent application and applied to “materially” different claim language.


I.  Claim Construction Issue

The claim at issue is the following representative claim 1 of the ‘291 patent:

1. A septal defect closure device comprising first and second occluding disks, each disk comprising a flexible, biologically compatible membrane capable of being collapsed for passage through a catheter and elastically returning to a predetermined shape for tautly holding a portion of the membrane against a septum; a central portion of the membrane of the first disk being affixed to a central portion of the membrane of the second disk to define a conjoint disk . . . .

A preferred embodiment of the septal defect closure device is shown below:


In various claims the disks are described as being “affixed,” “joined,” or “connected” to one another forming a “conjoint” structure. The district court construed the claims as requiring two physically separate disks.

The CAFC reviewed the claim language, the specification and prosecution history to assess whether the district court’s construction was proper.  The court characterized claim 1 as explaining “that the ‘conjoint disk’ is formed by ‘affix[ing]’ the membranes of the ‘first and second occluding disks’ to one another.”  Thus, the court implies a requirement of forming the conjoint disk by affixing the disks.

Regarding the specification, the court stated that every embodiment in the specification requires two separate disks that are attached to each other.  In the prosecution history, the University distinguished prior art reference King by stating that King’s device includes two membranes supported by umbrella-like radial frames, which are individually delivered through a catheter, and then connected at a central hub once inside the heart.  The University stated that its invention included two disks each formed of a membrane and frame that were advantageously assembled prior to insertion in the catheter.  The court also cited an Examiner’s reasons for allowance in a related application having similar claim language.  A reason for allowance was the inclusion of the limitation “a first membrane is connected to a central portion of a second membrane to form a conjoint disk.”

In a footnote, the court noted that during prosecution of the European counterpart application, the University distinguished a Russian device which was made in one piece with a tubular part, and stated that this does not correspond to two disks with a central portion of a first disk being affixed to a central portion of a second disk.

The University argued that the district court improperly imported process limitations into the claims.  However, the court stated that “[w]ords like ‘affixed’ or ‘conjoint,’ which read in context, describe the product more by its structure than by the process used to obtain it, are product limitations, not process limitations.”  The court also warned that “[w]hen a patentee chooses to use these words, they should be given their ordinary meanings with respect to the claimed product’s structure.”

Based on the construction requiring that the disks are two physically separate structures, the court found no infringement of AGA’s devices because AGA’s devices “are not constructed from two physically separate disks.”

II.  Disclaimer Issue


A patented invention is anticipated by a prior art reference if that reference discloses all elements of the claimed invention, including means-plus-function structures or their equivalents.

A disclaimer made during the prosecution of a patent application may operate as a disclaimer with respect to later patents of the same family.  However, a prosecution disclaimer will only apply to claims of a subsequent patent if the claims contain the same or substantially the same claim limitation as its predecessor.  An exception to this rule is if the disclaimer is directed to the scope of the invention as a whole and not to a particular claim.


The limitation at issue is in claim 1 of the ‘281 patent which recites in part:

a self-expanding structure exhibiting a spring-like behavioural component for moving the member between a compressed orientation . . . and an expanded orientation

This limitation was regarded as a means-plus-function limitation, and two corresponding structures were identified in the specification one of which is “a flexible, elastically deformable frame carried around the periphery of the member” (the “peripheral frame structure”).  The prior art reference “Lock” discloses neither of the corresponding structures.  However, the district court stated that Lock has a radial umbrella-like frame that was an equivalent of the peripheral frame structure in the claimed device because it performed the same function, in substantially the same way, with substantially the same result as the peripheral frame structure.

The University argued that during prosecution it disclaimed the use of a radial frame as an equivalent of the peripheral frame.  However, their argument is based on statements made in a predecessor application having different claims using different language.  The claim at issue in that application recited:

A septal defect closure device comprising first and second occluding disks, each disk comprising a flexible, biologically compatible membrane having a periphery, and an elastically deformable frame carried about the periphery of the membrane.

The University distinguished prior art reference “King” stating that the King device has an umbrella-like radial frame instead of a frame extending along the periphery of the membrane of each disk.  The claim was also amended to explicitly recite “a frame which extends along the periphery of the disk.”

The court agreed that the University disclaimed King’s radial frame with respect to the claim language describing the “elastically deformable frame” in amended claim 1 of the ‘951 application.  However, the issue is whether this disclaimer applies to the means-plus-function limitation of claim 1 of the ‘281 patent.

The claims of the ‘281 patent do not include a peripheral frame limitation.  But the University argued that the peripheral frame structure in the specification is corresponding structure of the means-plus-function limitation.

The court stated that the question is whether “the scope of the claim limitation is substantially the same in the subsequent application as it was in the earlier application.”  In this case, the court concluded that the scope of claim 1 in the ‘281 patent is not the same as in the ‘951 application, and thus, it would be inappropriate to apply the disclaimer in the ‘951 application to limit the range of equivalents in the ‘281 patent.

Since the University was unable to narrow the claims through disclaimer, the claims were held to be anticipated.


Regarding the claim construction issue, to obtain broader claim coverage, an applicant should try to include claims describing the completed apparatus without using terms such as “affixed,” “attached,” “joined,” etc.,  that can be interpreted as describing how the apparatus was made.  Of course, the application should also include claims using the noted terms as narrower claims in case the broader claims are invalidated.

The disclaimer issue was included to demonstrate an interesting attempt at using disclaimer.  Whether you are defending against infringement or you are the patent owner trying to avoid invalidation, prosecution disclaimer will not attach from a predecessor application unless the claim terms or the scope of the terms are substantially the same.

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