Claims vs. Description of the Invention

A utility patent is not a simple thing to understand. In a typical utility patent, you’ll see a bunch of drawings labeled as Figures and paragraphs of text. Somewhere in the text is a description with numerals referring back to the figures. Towards the end of the document, a section entitled Claims appears with numbered paragraphs. How do we make sense of all this? Where is the description of the invention? What is the difference between claims and the description of the invention?

What is the purpose of the claims?

A patent gives you the right to exclude others from doing your invention. By doing, we mean using, selling, manufacturing and advertising. Claims define exactly what you get to block others from doing. How can you tell if someone is infringing your patent? When it comes to utility patents, you can’t just eyeball it. You must go to the claims and perform a detailed technical analysis. You’re trying to figure out if your competitor has crossed the line, and the claims tell you where that line is drawn.

In a utility patent, you will find at least one independent claim typically followed by a number of dependent claims. There is a certain hierarchy in utility patent claims that requires training in order to understand the coverage and then compare the coverage to an accused product.

What is the primary purpose of the description of the invention?

Unlike the claims, the description of the invention do not define the boundaries of your legal rights. It is possible for your description to contain a great deal of extraneous details that never make it to the claims. Therefore, it would be a mistake to read the description and conclude that a product does not infringe because the description mentions certain features absent in the product.

The purpose of the description is not to define your patent rights. Instead, the description of the invention provides the details required to support the claims. When you file a utility patent application, your claims will likely undergo rejections by the patent examiner who thinks your claimed invention is already covered by the prior art. Your patent attorney may then respond by amending the claims to add further details in order to distinguish over the prior art inventions found by the examiner. In order to add those further details to the claims, your description of the invention must discuss those features.

In other words, you cannot amend your claims to add new features that are unsupported by your description of the invention. So your description of the invention provides a supply of different features for you to pick and choose in writing and amending your claims. This is the primary purpose of your description of the invention. If your description is scant, you will likely have a low inventory of features at your disposal.

What is a secondary purpose of the description of the invention?

Remember how I mentioned that your description may contain a bunch of extraneous details that never make it to the claims. Would those extra details serve any purpose besides filling up the document with verbiage? Yes, those disclosures can serve a defensive objective in blocking future applicants from patenting what you already described.

Keep in mind that patents should be granted only for those inventions that are novel and nonobvious. Your entire description will serve as prior art against subsequent patent filers, even if certain features never get claimed. It’s your description, and not the claims, that blocks future patents. This is true of published patent applications that never get granted. In this sense, a published patent application is similar to a white paper or other publicly available literature that can be cited by a patent examiner to show that certain ideas were already known as of a prior date.

What are differences in drafting claims and the description?

Given their differing purposes, the claims and description are written quite differently. Claims are typically written with terse language. Less is more when it comes to claiming an invention.

On the other hand, the description will usually contains tons of detail. The untrained eye reading the description may feel concerned about their invention being described so specifically, not realizing that their invention will be defined by the claims.

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Vic Lin

Startup Patent Attorney, Cofounder at Innovation Capital Law Group
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