Consider a Prosecution History Disclaimer for Every

Continuation ApplicationMichael V. Messinger & Jon E. Wright

July 2007

Consider a Prosecution History Disclaimer

for Every Continuation Application

Michael V. Messinger and Jon E. Wright

Patent owners and practitioners should consider modifying their continuation practice in

light of a recent case from the Federal Circuit. In Hakim v. Canon Avent Group, the court

appeared to lay down strict requirements for practitioners using continuation applications to

broaden unnecessarily narrow claims and clarify unnecessary estoppels created during

prosecution of parent applications. In Hakim, the court relied on statements made during

prosecution of a parent application to narrowly construe a claim term that was explicitly

broadened in the child application. The court ruled that the applicant's efforts to disclaim the

perceived estoppel were insufficient.

In a case involving "sippy-cup" valves, patent owner Hakim argued around asserted prior

art references by pointing to two separate mechanisms used to prevent leakage. The first

mechanism was a flexible valve material having a "slit" therein that responds to suction. The

second mechanism was a "blocking element" against which the "slit" rested when in a relaxed

position. Hakim stated that "[n]one of the references cited in the Office Action � teach or

suggest such a no-spill mechanism having a slit sitting against a blocking element such as recited

in all of the pending claims." The Examiner allowed the pending claims.

Believing that the term "slit" was too narrow, Hakim filed a continued prosecution

application, or a CPA. The CPA was accompanied by an attorney letter stating that Hakim was

broadening claims 1 and 2, and an amendment changing "slit" to "opening." The continuation

claims were allowed with no further comment or rejection by the examiner, and issued in U.S.

Patent No. 6,321,931 ("the '931 patent").

Hakim sued Cannon Avent Group ("Avent") alleging that its sippy-cup valves infringed

Hakim's '931 patent. The Avent valves had a hole in the flexible valve material, instead of a slit.

A key issue became how to construe the term "opening" in the '931 patent. Despite the Hakim's

attempt to broaden the claims in the continuation application, the district court narrowly

construed the '931 claims to a sealing mechanism that includes a flexible valve material or

diaphragm having a slit. The district court stated: "Because Hakim did not retract any of his

arguments distinguishing the prior art, he is held to the restrictive claim construction he argued

during prosecution of the patent." The court thus ruled on summary judgment that Avent's

devices did not infringe.

On appeal to the Federal Circuit, Hakim argued that the district court improperly relied

on the arguments he made during prosecution of the abandoned parent application. According to

Hakim, he avoided any perceived estoppels that may have crept into his claims by re-filing his

application with the broader claims, and explicitly flagging the change to assist the examiner.

Avent, on the other hand, argued that the totality of the prosecution history nonetheless limits

Hakim to the embodiment with the slit. Avent stressed that "when Hakim wrote to the examiner

that he was broadening the claims, he did not specifically point out that he no longer intended to

be limited to the specific mechanism that he had previously argued was the distinguishing feature

of his invention." (Slip op. at 5-6.)

In a unanimous decision, the Federal Circuit panel affirmed the district court ruling. The

court acknowledged that Hakim "had the right to refile the application and attempt to broaden the

claims." (Slip op. at 6.) However, the court also stressed the well known doctrine of prosecution

history estoppel, noting that "an applicant cannot recapture claim scope that was surrendered or

disclaimed." Relying on the public notice function of the patent and prosecution history, the

court stated: "Although a disclaimer made during prosecution can be rescinded, permitting

recapture of the disclaimed scope, the prosecution history must be sufficiently clear to inform the

examiner that the previous disclaimer, and the prior art that it was made to avoid, may need to be

revisited."

It is well settled that the prosecution history of related cases is relevant intrinsic evidence

that may be considered during claim construction. With this ruling, however, the Federal Circuit

made it clear that simply filing a continuation application with broader claims is not sufficient to

overcome or disclaim arguments made over the narrower claims during prosecution of the

parent. This is true even where the applicant explicitly advises the examiner that the

continuation claims are broader than those in the parent. To pursue broader claims than argued

previously, an applicant may now have to make an explicit disclaimer by informing the examiner

of pertinent art cited in the parent application, and arguments made to avoid it.

In view of Hakim, the authors suggest patent owners and practitioners reconsider their

current continuation application practice. This is especially true where continuations are filed to

broaden unnecessarily narrow claims or to clarify unnecessary estoppels that may have crept in

during prosecution of the parent. One solution may be to include a blanket disclaimer such as

the following:

The claims in the instant application are different than those of the parent application or other related applications. The Applicant therefore

rescinds any disclaimer of claim scope made in the parent application or

any predecessor application in relation to the instant application. The Examiner is therefore advised that any such previous disclaimer and the

cited references that it was made to avoid, may need to be revisited.

Further, the Examiner is also reminded that any disclaimer made in the

instant application should not be read into or against the parent application.

In sum, any continuation application should be evaluated with the lessons of Hakim in

mind. Whether using a blanket disclaimer, or something more specific, applicants should

explicitly and directly disclaim previous statements that could unnecessarily carry forward and

contaminate continuation claims. Existing patents issued from continuation applications may

also need to be reviewed with care where continuation disclaimers are absent.

Such continuation disclaimers are a new animal. Time will tell whether they will be

effective. Hakim, if read broadly, may be a new hurdle to filing successive continuations in U.S.

patent practice. On the other hand, practioners may be able to harness continuation disclaimers

to keep the door open for continuation practice and clearly overcome prior estoppels.

This article reflects the present thoughts of the authors, and should not be attributed to any of Sterne, Kessler,

Goldstein & Fox P.L.L.C. former, current, or future clients. The content is for purposes of discussion and should not

be considered legal advice. Copyright 2007 Sterne Kessler.

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