This blog has had numerous posts on negative limitations. Why? Negative limitations are extremely valuable to patent applicants in distinguishing prior art, particularly when examiners apply unexpected and arguably overly-broad interpretations to claim elements. Unexpected prior art is another example that highlights the value of strategic negative limitations, in that negative limitations can carve out just enough of the prior art as is needed without leaving too much on the table - like surgical removal of only as much tissue as necessary to excise a tumor, as opposed to cutting off a limb just because a region of the arm is infected.
The case law on whether an applicant has support to add a negative limitation provides rules that can leave a lot of room for interpretation. Some examiners take a very narrow view - only allowing a negative limitation if explicitly and exactly supported by the original specification. (BTW - the EPO is in a whole other category -- even with explicit support you might have to add the entire sentence or paragraph that goes with it to avoid intermediate generalization problems). The case law is not so narrow, but it can be difficult to convince some examiners otherwise. That leads to drafting techniques where drafters try to bake in negative limitations, often guessing as to how claims may be interpreted or what prior art may arise in prosecution. While strategically important, this crystal ball work can be difficult without years of experience in the field, and even then it is guesswork.
In the recent Novartis case (link here), the Federal Circuit provides another example of a relatively permissive approach to negative limitations added during prosecution which have no literal support.
Claim 1 of the patent:
A method for reducing or preventing or alleviating relapses in Relapsing-Remitting multiple sclerosis in a subject in need thereof, comprising orally ad-ministering to said subject 2-amino-2-[2-(4-oc-tylphenyl)ethyl]propane-1,3-diol, in free form or in a pharmaceutically acceptable salt form, at a daily dosage of 0.5 mg, absent an immediately preceding loading dose regimen
At issue was the so called no-loading-does limitation. The case provides some good quotes that might also help move some examiners that apply a heightened standard for negative limitations. These include the following:
It is well established that there is no “new and heightened standard for negative claim limitations.” Inphi Corp. v. Netlist, Inc., 805 F.3d 1350, 1356 (Fed. Cir. 2015). We are aware of no case that suggests otherwise. And, while HEC asserts that “[i] t is well-settled law that silence alone cannot serve as a basis for” a negative limitation, Appellant’s Br. 41, HEC identifies no case that actually supports that proposition. To the contrary, we repeatedly have resisted imposition of heightened written description standards for negative limitations, such as that urged by HEC.
Especially helpful is the mention of the MPEP language, which examiners love to cite when essentially applying a heightened standard of written description for negative limitations:
The dissent notes that the Manual of Patent Examining Procedure (“MPEP”) states: “The mere absence of a positive recitation is not a basis for an exclusion.” MPEP § 2173.05(i). As the dissent puts it—“silence alone is insufficient.” Dissent at 4. Both the MPEP and the dissent are correct in their statement of the law: the “mere absence of a positive recitation” is not enough and “silence alone is in-sufficient.” But the dissent, like HEC, ignores that it is how a skilled artisan reads a disclosure that matters. Written description may take any form, so long as a skilled artisan would read the disclosure as describing the claimed invention.
In this particular case, there was evidence that the specification conveyed to a person of ordinary skill that the inventor was in possession of the claimed invention. For example, the district court concluded that the “EAE model and the Prophetic Trial . . . both indicate to a person of ordinary skill that the claimed invention did not include the administration of a loading dose.” In prosecution, an expert declaration thus makes sense as a way to successfully overcome a written description rejection for a negative limitation.
The defendant tried to put a squeeze on the applicant by applying prior art that was also silent on the no-loading-dose limitation. If the patent was somehow valid, they argued, then the prior art should not be disqualified or faulted for failing to exclude the loading dose. While at a general level this argument has appeal, the majority found that there was a difference in the perspective of the person skilled in the art when reading the two different disclosures. That perspective, while confirming disclosure of the no-loading-dose in the granted patent, did not do so in the prior art (which was an abstract, and thus assumed not to be complete).
So, when you need that negative limitation in prosecution, the Novartis case may help convince the examiner that there is proper support if the specification can sufficiently show possession.
*if you are wondering about the image, that’s the instrument panel of a 1967 Mercury Cougar in original condition - 3 pedals and 3 forward gears - what more do you need?