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Santarus v. Par Pharmaceutical: Rader and Newman Disagree on Written Description Support for Negative Limitations

Did Chief Judge Rader mean to create a more strict disclosure requirement to support negative limitations in patent claims?

Last week the Federal Circuit decided the case of Santarus, Inc. v. Par Pharmaceutical, Inc., which dealt with whether a drug covered by an Abbreviated New Drug Application (ANDA) infringed the patents owned by that patent owner relative to the proton pump inhibitors (PPI) product omeprazole.  The big issue in the case is what might at first glance seem to be a rather innocuous statement relative to the support necessary in a patent specification for a negative claim limitation.  But after reading the Newman dissent (which joins in the other aspects of the Court’s decision) it starts to become clear that this could be a much larger issue of significant consequence.

The appeal came to the Federal Circuit from the judgment of the United States District Court for the District of Delaware. The plaintiff, Santarus, Inc., is the exclusive licensee of patents on specified formulations of benzimidazole PPI – a class of chemical compounds that inhibit gastric acid secretion and help prevent and treat stomach acid-related diseases and disorders. The patents are for the inventions of Dr. Jeffrey Phillips, and are assigned to the University of Missouri. Santarus provides the PPI product omeprazole in the formulations covered by the Phillips patents, with the brand name Zegerid®.

Prescription omeprazole is used to treat gastroesophageal reflux disease (GERD), a condition in which backward flow of acid from the stomach causes heartburn and possible injury of the esophagus (the tube between the throat and stomach). Prescription omeprazole allows the esophagus to heal and prevents further damage, and can also be used to treat conditions in which the stomach produces too much acid. See Omeprazole from NIH.gov.

The defendant Par Pharmaceutical, Inc. filed an ANDA seeking FDA approval to sell a generic counterpart of the Santarus Zegerid® products. This, of course, invokes the Hatch-Waxman Act, which allows a procedure known as a “Paragraph IV certification,” 21 U.S.C. § 355(j)(2)(A)(vii)(IV), whereby an entity that seeks to market a generic counterpart of a patented drug product or method of use, before the patent has expired, may challenge the patent before actually marketing the drug. The patent owner is allowed to treat an ANDA with a Paragraph IV certification as an act of infringement despite no truly infringing activities. In other words, the mere filing of a Paragraph IV certification is an act of technical infringement as defined by the statute. As with all Paragraph IV related patent infringement cases, the parties litigated the issues of infringement, validity, and enforceability of the Phillips patents.


The district court found that Par’s ANDA products infringed the Phillips patents, but held all of the asserted claims invalid on the ground of obviousness, 35 U.S.C § 103. The district court also held certain claims invalid on the ground of inadequate written description, 35 U.S.C. § 112. On the defense of unenforceability, the district court held that there was not inequitable conduct by Dr. Phillips, the University of Missouri, or their counsel in procuring the patents.

Both parties appealed the various adverse rulings with one notable exception. Par did not appeal the finding of infringement.

The Federal Circuit, per Chief Judge Rader and with Judges Moore and Newman, concluded that the district court erred by holding that some of the thirty-six asserted claims would have been obvious over the prior art; these rulings are reversed. The court’s other rulings were affirmed.

Of particular note is the disagreement between Judge Newman and the majority on one seemingly minor point related to written description. Chief Judge Rader wrote:

“Negative claim limitations are adequately supported when the specification describes a reason to exclude the relevant limitation.”

Judge Newman characterized this as “a gratuitous fillip,” saying that this is the creation of a “new rule that the specification must ‘describe a reason’ for the claim limitation, or the claims are invalid on written description grounds.” Judge Newman went on to explain: “Negative claim limitations may often be appropriately stated in claims al- though the reason for the limitation is not set forth in the specification.”

Judge Newman identified several situations where negative limitations are allowed although no specific reason for the limitation may be found in the patent specification:

  • “a negative limitation may be prudently placed in a claim in response to an exam- iner’s rejection, perhaps to distinguish a reference that was given its “broadest reasonable interpretation” for purposes of examination.
  • “A claim limitation may distinguish the prior art al- though the reason is not in the specification.”
  • “there may be situations in which comparative data are provided during prosecution in order to respond to an examiner’s rejection, see MPEP §716, and the distinction from the prior art may lead to a claim limitation.”

Judge Newman concluded:

“The applicant’s obligation is to describe and claim the invention in accordance with 35 U.S.C. §112. Thereafter, patent examination may lead to amendments to the claims. The MPEP §2173.05(i) advises that: “If alternative elements are positively recited in the specification, they may be explicitly excluded in the claims.” The MPEP does not require that the reason for such exclusion must be stated in the specification. The panel majority creates a new and far-reaching ground of invalidity, a ground that received no deliberation and advice from the concerned communities.”

A seemingly small issue, but one of potentially large significance. If Chief Judge Rader meant to say that the only way for a specification to support a negative limitation is to announce a reason for the limitation then that would seem to be an important departure from written description law as we have known it to exist and would create a scenario where it would be exceptionally difficult to have support for many negative limitations that need to be inserted in claims as the result of the natural ebb and flow of prosecution with the patent examiner.

So did that one line in the opinion usher in a new written description requirement? If Chief Judge Rader and Judge Moore did not intend to say this quite as definitively as it might be interpreted one could easily speculate that the language would have been softened or somehow changed after Judge Newman drafted her opinion. The fact that the language persists in the released opinion would seem to be strong support for the proposition that the statement was intentional and does potentially usher in a new regime insofar as disclosure of negative claim limitations is concerned.


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Join the Discussion

13 comments so far.

  • [Avatar for MaxDrei]
    September 11, 2012 09:00 am

    In recent years, there is no topic that has taken up more time than “disclaimers in claims” at Europe’s Supreme Court on the substantive law of the validity of patents, the Enlarged Board of Appeal of the EPO. It’s a tough one.

    Until recently there has been room in Europe for different opinions, passionately held. Your passion depends of course, on whether you are the party holding the trigger or the one looking down the barrel, the one threatening infringement proceedings or the one having to defend against them.

    So I sympathise with both CAFC writers. Paul Cole, do you want to comment?

  • [Avatar for EG]
    September 11, 2012 09:27 am


    I agree with Judge Newman on the “negative limitation” issue as it relates to the “written description” requirement. The reason for the “negative limitation” may be relevant for the purposes of 35 USC 103, but it isn’t relevant to the written description” requirement under 35 USC 112, 1st paragraph for the reasons stated by Newman.

  • [Avatar for American Cowboy]
    American Cowboy
    September 11, 2012 09:58 am

    I have cases like this from time to time. The examiner cites a reference that she says makes the claims unpatentable, largely because we claimed the invention broadly, in fact, broadly enought to read on this seemingly out of the blue reference that disclosed X. We added negative limitations to the claims to say something to the effect, that the claim should not be construed to read on X. X had never been discussed or disclosed in the spec or drawings.

    Clearly, this is a mention of a new item, but it is not a CLAIMING of a new item, but rather a disclaimer of the new item. Who give a rats patooey if the original spec did not say we disclaim x? What public policy if furthered by a constipated construction of the written description requirement to make such an amended claim invalid?

  • [Avatar for Gene Quinn]
    Gene Quinn
    September 11, 2012 01:31 pm

    I can see both positions. I tend to lean more toward Judge Newman’s view, but I could envision situations where the specification would not be able to support the addition of a particular limitation that one tries to enter into a claim. But that is not only a problem for negative limitations, it is a problem generally.

    Rather than a specific statement like the one made by Judge Rader, which can and almost certainly will be abused and misinterpreted, I would prefer to simply ask whether the specification fairly discloses the negative limitation so that one of skill in the art would understand it to be in possession of the inventor. After all, that is what 112, 1st paragraph is all about anyway.


  • [Avatar for American Cowboy]
    American Cowboy
    September 11, 2012 01:51 pm

    “I would prefer to simply ask whether the specification fairly discloses the negative limitation so that one of skill in the art would understand it to be in possession of the inventor.”

    Gene, in my example, the negative limitation actually does limit the scope of what was a previously broader claim. The inventor is simply saying the patent analogy to “my land does not stretch as far as the eye can see as I previously claimed, but rather stops at that fence that I just put up.” Why should that change in position justify taking away ALL of his land?

  • [Avatar for Anon]
    September 11, 2012 03:20 pm


    The quick and easy answer will come from the person who land the post lands on (but does not belong to the inventor). If the inventor does not rightfully own the land “as far as the eye can see,” for example, because he does not enable that vista of scope, arbitrarily pulling back and setting a fence post just anywhere is no guarantee that the fence post has landed on the inventor’s rightful territory.

    Gene’s analysis simply boils down to: was the limitation introduced in the possession of the inventor as witnessed by the filed document?

  • [Avatar for American Cowboy]
    American Cowboy
    September 11, 2012 03:47 pm

    “was the limitation introduced in the possession of the inventor’
    Why is this the issue?

    Shouldn’t the issue be “was the subject matter encompassed by the amended claim, that has the new limitation as a boundary, in the possession of the inventor?”

  • [Avatar for Paul Cole]
    Paul Cole
    September 11, 2012 05:16 pm

    One of the problems of my colleagues in the US is an over-concentration on dicta in recent cases. A judge may put forward an apparent rule that appears pertinent to the case before him or her. But only subsequent case-law will show whether the rule is of general application or relates to a more specific factual situation.

    In the present case there was a reason in the specification to support the proposed disclaimer, the court relied on that reason and held that the disclaimer was supported under 35 USC 112. Bit it does not follow that ALL disclaimers require a specific reason in the specification – some should and some need not as European experience adequately demonstrates.

    In this case the dissent may not be altogether helpful in the vehemence with which the proposed rule is condemned. Better, perhaps, to treat the proposed rule as a mere dictum which in its broader aspects should not be of binding or even persuasive authority for later decisions.

    It is interesting what president Lincoln said about the Supreme Court in his first inaugural:

    “I do not forget the position assumed by some that constitutional questions are to be decided by the Supreme Court, nor do I deny that such decisions must be binding in any case upon the parties to a suit as to the object of that suit, while they are also entitled to very high respect and consideration in all parallel cases by all other departments of the Government. And while it is obviously possible that such decision may be erroneous in any given case, still the evil effect following it, being limited to that particular case, with the chance that it may be overruled and never become a precedent for other cases, can better be borne than could the evils of a different practice. At the same time, the candid citizen must confess that if the policy of the Government upon vital questions affecting the whole people is to be irrevocably fixed by decisions of the Supreme Court, the instant they are made in ordinary litigation between parties in personal actions the people will have ceased to be their own rulers, having to that extent practically resigned their Government into the hands of that eminent tribunal.”

    In addition to his political and personal equalities, Lincoln was a first-rate lawyer. His warning that questions of wide general importance should not be irrevocably decided in ordinary litigation between individual parties deserves wider and more current recognition.

  • [Avatar for EG]
    September 11, 2012 05:32 pm

    To all:

    As Judge Newman said, a reason for the “negative limitation” is not required for the “written description” requirement. But such a reason may be helpful for satisfying “written description” where the “negative limitation” is not “black & white” but by inference; from my reading of the facts, that appears to be the situation in the Santarus case. Having reason for the “negative limitation” also addresses anon’s comment about ensuriing that the inventor was, in fact, “in possession of the invention” at the time the application was filed.

  • [Avatar for Paul F. Morgan]
    Paul F. Morgan
    September 12, 2012 08:15 pm

    Should it not make a big 112 enablement difference whether the negative claim limitation was in a claim filed with the original application (and thus part of the specification), versus a claim limitation being added later? How can the latter possibly be validly done without specification support for that specific limitation?

  • [Avatar for Gene Quinn]
    Gene Quinn
    September 13, 2012 11:41 am


    That is exactly my point. I don’t think we can say that there would never be support for the addition of a negative claim limitation. Perhaps the drawings show something, or there are charts, tables or graphs. I wouldn’t require the negative limitation to be in an original claim, but it would have to be somewhere in the disclosure.


  • [Avatar for American Cowboy]
    American Cowboy
    September 14, 2012 09:43 am

    The mere absence of literal support for a claim limitation “does not, in and of itself, establish a prima facie case for lack of adequate descriptive support under the first paragraph of 35 U.S.C. 112.”Ex parteParks, 30 USPQ2d 1234, 1236 (BPAI 1993) (citations omitted).

    “[The] specification, having described the whole, necessarily described the part remaining.”In re Johnson, 558 F.2d 1008, 1019 (CCPA 1977). In Johnson, the court said “The notion that one who fully discloses, and teaches those skilled in the art how to make and use, a genus and numerous species therewithin, has somehow failed to disclose, and teach those skilled in the art how to make and use, that genus minus two of those species, and has thus failed to satisfy the requirement of s [sic] 112, first paragraph, appears to result from a hypertechnical application of legalistic prose relating to that provision of the statute.”

  • [Avatar for Tom Brody]
    Tom Brody
    March 28, 2013 04:40 pm

    THIS IS NOT LEGAL ADVICE. The Santarus decision did NOT state that a reason (advantage; disadvantage) was mandatory, when making arguments for written description support for adding a negative limitation to a claim during prosecution. I recently read all of the cases from the Board, regarding adding negative limitations during prosecution. Usually, the Board does NOT require any advantage/disadvantage to be disclosed in the specification, when it holds that the negative limitation does, in fact, have written description support. But sometimes, the Board does observe that the specification include a statement of advantage/disadvantage. In this regard, the Board’s behavior is arbitrary. And so, it seems to me that the Federal Circuit’s requirement, in Santarus, to require that the specification disclose an advantage/disadvantage was just as arbitrary. The next issue of AIPLA Quarterly Review will include my article on the topic. For my article, I read all 250 cases from the Board, as well as the miniscule number of cases from the Federal Circuit, on negative limitations. THIS IS NOT LEGAL ADVICE.