Federal Circuit Imposes Heightened Standard for Written Description Support of Negative Claim Limitations

Harris Beach PLLC

In Novartis Pharmaceuticals Corp. v. Accord Healthcare, Inc., the U.S. Court of Appeals for the Federal Circuit (“Federal Circuit”) held patent claims invalid for lack of written description where a negative limitation was not “necessarily excluded” by the specification, reversing the district court’s judgment finding adequate written description.  See Case No. 2021-1070 (June 21, 2022).  The Federal Circuit found that the claim limitation “absent an immediately preceding loading dose” lacked written description because the patent “fail[ed] to disclose the absence of a loading dose” and the specification’s silence on the loading dosage did not satisfy written description.  Id. at 2.  Although the written description requirement does not require a negative limitation to be recited verbatim in the specification, the language of the specification must indicate that the inventor intended exclusion.  A person of ordinary skill in the art, reading the specification, must “understand [the] negative limitation to necessarily be present in the disclosure.”  Id. at 12.

This decision underscores the need to describe all possible permutations of the claims in the patent specification, including the removal or substitution of key elements.  While it may be difficult to predict the need for a negative limitation during the drafting phase, an understanding of the differences between the closest prior art and the current claims may help to identify elements that, by their absence, may demonstrate the novelty or non-obviousness of the claims during prosecution.  This case represents yet another reminder of the importance of making the specification as robust as possible before filing. 


The claimed methods to treat relapsing remitting multiple sclerosis recited a 0.5 mg daily dosage of fingolimod hydrochloride without an immediately preceding “loading dose.”  A “loading dose” is higher than a daily dose and is usually given first to increase therapeutic levels quickly.  The limitation was added during prosecution to overcome a prior art objection.  

The specification described an experiment where relapse was completely inhibited in rats given a daily dosage of 0.3 mg/kg.  The specification also described a prophetic human trial where patients would receive 0.5, 1.25 or 2.5 mg per day for 2 to 6 months.  The specification also detailed a wide range of potential dosages.  The district court had found that the no-loading dose limitation was satisfied because the specification did not recite a loading dose and because the prophetic human trial referenced the dosage as starting “initially.”

The Decision

Notably, the Federal Circuit had previously affirmed the district court’s determination that the claims satisfied the written description requirement of 35 U.S.C. § 112.  Novartis Pharmaceuticals Corp. v. Accord Healthcare, Inc., 21 F.4th 1362 (Fed. Cir. 2022).  Thereafter, the court granted the petition of HEC Pharm Co. Ltd. and HEC Pharm USA Inc. for rehearing, vacated the prior decision and reversed the district court’s determination that the claims were not invalid.  Novartis Pharmaceuticals Corp. v. Accord Healthcare, Inc., Case No. 2021-1070 (June 21, 2022).

 Although the Federal Circuit noted that whether a claim satisfies the written description requirement is an issue of fact that is reviewed for “clear error” and that inadequate written description must be shown by “clear and convincing evidence,” it overturned the district court’s decision finding that the negative limitation was adequately disclosed.  Id. at 4. 

To provide support for a negative limitation, the specification must either describe a “reason to exclude” the element recited in the negative limitation or “‘distinguish[ ] among’ the element” and its alternatives.  Id. at 5.  “Silence is generally not disclosure.”  Id.  Although the written description requirement does not require a negative limitation to be recited verbatim in the specification, the language of the specification must indicate that the inventor intended exclusion.  Silence may satisfy written description only in those situations where a skilled artisan would understand the specification as inherently disclosing the limitation—where the “patent owner [can] establish that a particular limitation would always be understood by skilled artisans as being necessarily excluded from a particular claimed method or apparatus if that limitation is not mentioned.”  Id. at 7.

The Federal Circuit found the district court’s determination that the term “initially” supported the negative limitation to be in error, stating that the term “initially” related to the length of treatment, not the dosage.  Id. at 7.  Further, the disclosure of a daily dosage does not constitute disclosure of a no-loading dose, because otherwise the claim would not have had to be amended to add the limitation.  Id.  And, despite expert testimony that, if there were to be a loading dosage, it would have been stated in the specification immediately before the treatment, the Federal Circuit found the limitation to be unsupported because the experts did not testify that a person of ordinary skill in the art “would understand silence regarding a loading dose to necessarily exclude a loading dose.”  Id. at 11 (emphasis in original).  Because the limitation lacked written description report, the Federal Circuit vacated the district court’s judgment that the claims were not invalid for written description.  

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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