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The New Patent Law in New Zealand

Preemptive Drafting Approaches to Negative Claim Limitations That May Be Added in Post-Filing Prosecution

6 years ago


The CAFC has issued a decision in Santarus, Inc., et al., v. Par Pharmaceutical, Inc., Case No. 10-1360 (Fed. Cir., Sept. 4, 2012), holding that to provide adequate support for a negative claim limitation, the specification must describe a reason to exclude the relevant limitation.  The supplements the provision of MPEP Section 2173.05 (i) requiring a negative limitation to have a “basis” in the original disclosure.  The court’s decision permits a patentee to support both inclusion and exclusion of a same limitation.

Given the ubiquity of provisos, particularly in chemical practice, it will be necessary to address this issue in any instance in which specific ingredients, substituents, etc. may be excluded, so that we have a proper supporting basis for the negative limitation and yet do not disparage the invention when it includes such ingredients, substituents, etc. 

Accordingly, it may be desirable to take a formulational approach in the description, by description such as the following:

·        "In the broad practice of the present disclosure, in which the pH of the composition is desirably acidic, it may be advantageous to at least partially attenuate or even eliminate the neutralization agent. …"

·        "The R1 and R2 ring carbon substituents may exclude carboxyl substituents in applications in which latent esterification could result in phase separation of the composition. …"

This will require attention in drafting to support both the presence and absence of a potential negative limitation, but in view of the downside of invalidity of unsupported negative limitation-amended claims, the effort is correspondingly required as a matter of best practice.

Of course, one must always include in the specification a progression of increasingly narrow positively recited sub-groups, substituents, etc., to accommodate fall-back narrowing of claims that may be required in response to new prior art arising, but there will be instances in which a negative limitation or proviso affords the best approach to gaining the broadest possible claim scope, and the foregoing should be borne in mind.

Steven J. Hultquist


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