On Octopi and Myths of Claim Drafting: Negative Limitations and Empty Spaces

On Octopi and Myths of Claim Drafting: Negative Limitations and Empty Spaces


The plural of octopus is a funny word. Ask most people and they’ll tell you that it’s octopi. That conclusion is born from how to properly make Latin words plural. For example, the plural for the Latin-origin word radius is, when pluralized in Latin, radii. Many people and even the excellent Webster’s Third New International Dictionary naturally follow the Latin usage when tackling the plural form of octopus.
But there are at least three problems with octopi. First, besides the moment when some pretentious know-it-all tells you about “octopi,” your opportunities to  use a plural form of octopus in your life are seldom. (If you often need the plural for octopus, congratulations Jacques Cousteau–you need not bother with this article–you have a more interesting life than my normal reader.) The second problem with octopi is that no matter how they pluralize in Latin, we are talking about making plurals in English. And in English, the plural of octopus is octopuses
It’s at the third problem of octopi that you can pop the pretentious bubble that surrounds the person with the upturned-pinky-while-drinking-tea. You see, octopus is not a Latin word. Not ever. Octopus is a Greek word. The plural of octopus in Greek is octopedes. An octopus traveling with friends would never would turn to octopi, even in the Mediterranean of 1200 years ago. FN1
Octopi is a myth that’s been busted. And the very same grammar-wannabes who advocate for it are probably also pushing claim drafting myths like “You can’t claim negative limitations” and “You can’t claim holes.” While these pieces of advice may be good in specific claim-drafting situations, there’s no “can’t” attached to them.
The Myth of Claiming Negative Limitations
A negative claim limitation reads like nails on a chalkboard to most claim drafters. There’s almost always a better way to draft a claim, but such a limitation is permitted. Take for example the following claim that the Federal Circuit recently considered in Inphi Corp. v. Netlist, Inc.:

1. A memory module comprising: a plurality of memory devices, …a second number of chip selects equal to twice the first number of chip selects, wherein the plurality of memory devices comprises double-data rate (DDR) dynamic random-access memory (DRAM) devices and the chip selects of the first and second number of chip selects are DDR chip selects that are not CAS, RAS, or bank address signals.


The Federal Circuit found this negative limitation not invalid because the patent’s specification supported it. As a claim drafter, the only questions to consider when looking at such a limitation are whether they provide advantageous claim scope and whether the specification supports the limitation. Whether the negative limitation itself is valid on its face is well-settled: Negative limitations are acceptable.
Myth. Busted.
The Myth of Claiming Holes and Empty Spaces
Once upon a time I had to claim a certain kind of nut and bolt combination. When claiming the nut, I recited the “hole” that ran through it. The partner overseeing my work delivered a stern lecture to me that “you can’t claim what’s not there. It’s impermissible in patent law.”Charmer that I was, I researched what sounded legally baseless and found it was. I returned the claim to the partner as I had drafted it with the research to support my position.
Grooves, apertures, openings, and similar empty spaces are acceptable elements and may be seen in thousands of patent claims. “Hole” appears in the claims of over 250,000 patents. Groove and aperture appear in almost 200,000 patents’ claims each. Opening appears in 640,000 patents’ claims.
In spite of this evidence, I don’t recommend my approach to dealing with your bosses.
Myth. Busted.
FN1. What then to make of Webster’s acceptance of octopi? Octopi pains me to my core. But English evolves over time and sometimes we accept new words and usages. Still, let’s beat this one back people.
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