Patent Prosecution Strategy: Negative Claim Limitation

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Negative restrictions are generally discouraged when formulating claims, according to popular opinion. When expressing a limitation, it is preferable to use positive rather than negative language. Most people agree that this is the best practice. Negative restrictions, or claim integers reciting the absence of a feature, are typically viewed as being less wise than their positive counterparts since they are more likely to be open-ended and may violate a number of patent law criteria. 

Table of Contents

Introduction  

In contrast to positive claim limitations, which state the presence of a feature, a negative claim limitation is a language included in a patent claim that refers to the absence of a feature. Words like “devoid,” “absence,” “without,” “(whatever) -less,” “not including,” “excluding,” and the like might be used to recite negative claim restrictions. They can be a powerful instrument to set your patent claims apart from those of the prior art if used appropriately. 

Negative constraints may be asserted in accordance with the Manual of Patent Examining Procedure (MPEP) § 2173.05(i) if they are explicit and supported by the specification. Negative restrictions must be supported by the first disclosure. A negative limitation is not justified by the simple absence of a positive recitation. 

Basis For Negative Limitation

The specification does not have to include the negative limitation word-for-word according to the MPEP. Otherwise, applicants would be unnecessarily burdened with having to explicitly state what is not included in their invention by having to describe every known item of the prior art. 

Examples of sufficient bases for negative limits include the following: 

  • The specification provides a justification for excluding the pertinent limitation (Inphi Corp. v. Netlist, Inc.). 
  • Specification describes alternatives (Santarus, Inc. v. Par Pharm., Inc.). 
  • Description of prior art in the specification discusses shortcomings of certain features drawings that show the presence of certain features which necessitates the absence of opposite features. 
  • Specifications specifically state when a feature is absent. 

Examples of bases for negative limitations that are insufficient include the following: 

  • attempting to avoid a reference to a prior art work by omitting nickel from a defined group of metals claimed for a metallic protective coating without offering a patentable justification for doing so (In re Langdon) 

Novartis Pharmaceuticals v. Accord Healthcare Inc. 

How much of the specification should be used for something that isn’t intended to be included in the claim? According to a recent Federal Circuit ruling in Novartis Pharmaceuticals v. Accord Healthcare Inc., the answer might not exist at all. The important thing, according to the decision, is that the negative limitation should not be described in the specification in a way that differs from how it is utilized in the claim.  

The drug fingolimod hydrochloride, which Novartis sells under the trade name Gilenya, is used to treat Relapsing-Remitting Multiple Sclerosis (RRMS) when given “at a daily dosage of 0.5 mg, absent an immediately prior loading dose regimen,” according to the patent claims at issue in Novartis. Defendants asserted, among other things, that the patent specification lacked sufficient 35 U.S.C. § 112 written description support for the negative claim limitation “without an immediately prior loading dose regimen,” in order to get approval to commercialize a generic version of the medicine. 

The parties concurred that “loading dose” refers to a dose that is larger than daily and “often provided as the first dose.” However, they couldn’t agree on the amount of information that had to be disclosed in order to satisfy the written description requirement for the specification’s negative “loading dosage” limitation. The patent specification “contains no recital of a loading dose ‘or its prospective benefits or disadvantages at all,'” according to the defendants, therefore the patentee failed to disclose the “loading dose fully.” 

In response, Novartis provided expert testimony and claimed that “if a loading dose were directed, the Patent would indicate that the loading dose should be delivered “immediately”.” According to Novartis’ expert, a person of ordinary skill would read the specification to explain the absence of a loading dose because the patents did not specify an initial loading dose. 

The district court sided with Novartis after a bench trial, recognizing the testimony of its expert and concluding that “although the patent provides various dosing regimens, such as “intermittent dosing,” it does not specify delivering those regimens with loading doses.” The specification thus “indicated to a person of ordinary skill that the claimed invention did not contain the delivery of a loading dose” and gave sufficient written explanations for the negative restriction, the court found. 

The Federal Circuit rejected the defendants’ claim that the specification had to at least allude to the harmful restriction’s “possible advantages or disadvantages…” The Federal Circuit argued that the defendants’ stance conflicted with earlier rulings that there is no “new and heightened test for negative claim restrictions.” Although the Novartis circumstance was not directly addressed by precedent, the Federal Circuit concluded that two precedent-related ideas were especially useful. 

A negative limitation cannot be “inconsistent with the disclosure,” according to the first rule, and still, satisfy the written description requirement. The second rule is that written description is sufficient where “‘the core of the original disclosure’ communicates the relevant information—regardless of how it conveys such information,” according to the Federal Circuit. 

Of course, even while a negative limitation may not need to be disclosed in the specification, doing so may still be beneficial. There might not have been a disagreement at all if, for instance, the Novartis specification had simply stated, “Do not deliver a loading dose.” Detailed information on the case is available at https://www.proskauerinlifesciences.com/wp-content/uploads/sites/34/2022/02/Novartis-v.-Accord.pdf.  

Conclusion

Lack of assistance would appear to be the key “danger” with unfavorable limitations (in the substantive sense). In reality, it is easier to fully describe a “positive” (existing) feature than a “negative” (missing or non-existent) one. Therefore, generally speaking, the description may be more likely to offer appropriate support across the entire range of the relevant integer for positive constraints. 

Arguments over description typically come up when attempts are made to make claims more specific in order to impede lawsuits. Additionally, it has been noted that the Federal Circuit is increasingly stricter in these types of procedures. As a result, as patent prosecution shifts, patent practitioners must adapt their methods as well. 

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