Avoiding Infringement is a Subtractive Process

abacus showing subtraction
When in doubt, subtract.

How do we avoid infringing others’ patents while obtaining the strongest patent possible for our own invention?

When we focus on protecting our intellectual property, we sometimes fail to consider the possibility of infringing on someone else’s patent. A common belief among inventors is that The US Patent and Trademark Office protects inventors from infringing. But although the USPTO will not grant a patent for something that’s already patented or already in the public domain, protecting existing patents is not their job. Their job is to determine whether we have the right to exclude others from making, using or selling what is ours. They bestow this privilege by granting patents; it is up to us not to infringe. So how do we avoid infringing other patents?

One way to do it is to research the prior art, understand the claims of the prior art, and subtract from them.

The USPTO tells us that “Infringement is determined primarily by the language of the claims of the patent.” It is the claims of our patent application that should be carefully written so as not to infringe on patents in force.

Let’s consider an existing patent for a unique type of shovel. A shovel with an S-shaped shaft and a T-shaped handle.

In “claiming” this invention (i.e., stating the claims of the invention), the inventor wrote:

1.      A shovel comprising:

a shovel head having a receiving portion and a blade portion; and

an S-shaped shaft having a first end and a second end; and

a T-shaped handle having a grip and a receiving portion, said first end of the S-shaped shaft fixedly engaged with said shovel head,

the first end of said S-shaped shaft fixedly engaged into said receiving portion; and

the second end of said shaft fixedly engaged with said receiving portion of said T-shaped handle; wherein

The assembled shovel, shaft and handle are used for digging.

This is the first claim, which is the most important one; the broadest claim which the inventor may make. All the subsequent claims of this patent will be more specific and narrower than this broad, first claim.

Now let’s say that we have invented a better shovel, one that could be part of a possible licensing deal. Our shovel is similar to the one in the above-mentioned patent, except ours has a long handle without the T-shaped grip. In applying for our patent we would construct our claims with care so as not to infringe on not only the first claim of the prior art, but each element of at least one of the claims of the prior art.

– Each element
– Of at least one claim
– Of a patent in force.

Reasonably, then, we might assume that if we don’t include each element of those claims, we would not be infringing. Right?

Almost. We don’t get to pick which claim we want to measure our invention against. We just have to be sure that our invention’s claims leave out at least one element of any of the claims of the existing patent in force.

For example, we might write our first claim as:

1.      A shovel comprising: a shovel head having a receiving portion and a blade portion; and

an S-shaped shaft having a first end and a second end; and

said first end fixedly engaged with said shovel head, the first end inserted and fixedly engaged into said receiving portion; wherein the assembled shovel is used for digging.

Here we have successfully left out at least one of the features (the t-shaped handle) of the patented shovel, while offering a new shovel that is both useful and novel.  In writing our claims, we have considered the cited patent and subtracted from it.

This of course does not guarantee success at the Patent Office. In fact they would likely respond that long-handled shovels without attached grips are common, and that this is an obvious, minor change and therefore not patentable. But you would, however, be allowed to make, use and sell your shovel with the S-shaped shaft and without the T-shaped handle.

Now let us suppose that another inventor were to come along and make a shovel just like yours, but with a weight scale built into the shaft (perhaps to allow bragging about how many pounds of gravel were shoveled), or one constructed with six screws instead of four. If everything else in this shovel were the same as yours, the inventor would still be infringing on your patent, because their invention added to your prior art.

It is up to the inventor, then, to first consider what is novel, useful, and innovative about their invention, and to avoid simply adding features. And when considering the prior art, subtraction is the verb to remember.

Copyright Keeley-DeAngelo. When quoting, cite the site.

No one here is a lawyer, and this is not legal advice.  As a patent agent, Scott Keeley is registered at the USPTO to prosecute patents. That means we do everything a patent attorney does except argue in court.

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