Patent Infringement Overview. Episode 76

Why Understanding Patent Infringement Matters

Initially, I had planned several episodes on how to invalidate someone else’s patent at the Patent Office using different approaches. However, I realized that before we dive into that, you need to understand why you might want to invalidate a patent. That brings us to today’s topic: a general overview of patent infringement and its different types.

Understanding Claims and Patent Infringement

If you haven’t listened to my previous episodes about the parts of a patent, particularly the claims section, I recommend going back to review them. When describing an invention in a patent application, you include various details, such as color or size. However, these details usually don’t determine why you actually received a patent. Instead, the claims section is where you define what you are claiming as your invention.

To illustrate, let’s look at Patent No. 5,839,395, titled Safety Leash, which is essentially a dog leash. The figures and description are relatively short—under a page—followed by the claims section. The first claim consists of parts A, B, C, and D. Here’s a simplified version:

1. "A shock-absorbing, automatically releasing dog leash holder comprised of:"

   • (A) A releasable loop through which a dog owner initially places their wrist.

   • (B) A handle to which the releasable loop and a dog leash are attached.

   • (C) Notches in part of the handle.

   • (D) An elastic, grooved, semi-cylindrical, finger-indexed body that slides over the notches to form a grip and trap air in the notches, absorbing shocks caused by sudden tugs from the dog leash.

The last part, which starts with whereby, is usually explanatory and not necessarily a limiting feature of the claim.

How to Determine Infringement

If you develop a dog leash and find this patent during a search, you may be concerned about infringement. The way to determine whether you are infringing is to go limitation by limitation and check if your product includes every element in the claim.

Let’s summarize the essential components:

• Part A: A releasable loop.

• Part B: A handle attached to the loop.

• Part C: Notches in the handle.

• Part D: An elastic, grooved, semi-cylindrical, finger-indexed body.

It appears that parts C and D contain the inventive aspect, as many leashes already have loops and handles. So, what happens if your design uses a prism-shaped grip instead of a semi-cylindrical one? Since a prism is geometrically different from a cylinder, you may have designed around this patent and avoided infringement.

Why Claim Drafting Is Crucial

This example highlights why patent claim drafting is critical. If the claim had used a broader term like elongated member instead of semi-cylindrical, it would have been harder to design around. A good patent attorney will anticipate potential workarounds and draft claims strategically to prevent easy design modifications that bypass infringement.

Direct Patent Infringement

If another leash contains all these elements, that product is directly infringing the patent. Direct infringement is the simplest form to understand. If the patented invention claims A, B, C, and D, and your product contains A, B, C, and D, you are infringing—regardless of whether your product also includes additional elements like E, F, or G.

Indirect Patent Infringement

There are two types of indirect infringement: inducement and contributory infringement.

Induced Infringement

Let’s say you don’t manufacture this leash but instead publish an article explaining how to build one using parts from a hardware store. If someone follows your instructions and creates an infringing product, you are guilty of induced infringement.

I personally know of a case where this happened. A researcher found a patent describing a chemical solution used in biological research. The patent’s instructions were simple: mix two readily available chemicals. The researcher posted online, saying, “You don’t need to buy this solution from the company—just mix these two chemicals and save money.” The patent holder sent a cease-and-desist letter, demanding that the post be removed.

Instead, the researcher could have phrased it differently: “I found a patent for storing RNA. It’s a simple chemical mixture. I don’t want to infringe this patent, but is there a way to achieve the same effect using different chemicals?” That way, they wouldn’t be explicitly inducing infringement.

Contributory Infringement

Now, let’s say you manufacture only Part D—the semi-cylindrical grip. You sell this component, knowing that customers can easily purchase Parts A, B, and C separately and assemble a complete infringing leash. If the sole purpose of Part D is to enable infringement, you are guilty of contributory infringement.

Patent law regarding foreign uses and contributory infringement is complex, with frequent court rulings defining its scope.

The Doctrine of Equivalents

A final concept to understand is the doctrine of equivalents. Typically, to infringe a patent, your product must contain each and every limitation in the claim. However, if your product includes an element that is equivalent to a claimed element, you might still infringe under this doctrine.

For example, if instead of a semi-cylindrical shape, your grip had 50 sides, it might look nearly identical to a cylinder. If a court determines that the function, way, and result of your design are substantially the same as the patented invention, you could still be found guilty of infringement under the triple identity test.

The doctrine of equivalents is not always clear-cut. The more a design deviates from the original claim, the harder it is to argue equivalence. But you never know how a judge or jury will rule. This is why claims should be drafted broadly enough to cover potential design modifications.

Summary of Patent Infringement Types

We covered the main types of patent infringement:

• Direct Infringement: When a product contains every element of a claim.

• Induced Infringement: Encouraging or instructing others to infringe.

• Contributory Infringement: Supplying a component with no other purpose except enabling infringement.

• Doctrine of Equivalents: When a product doesn’t literally match the claim but performs substantially the same function in the same way to achieve the same result.

  
  

I’m Adam Diament, and until next time, keep on inventing!