How to Write the Detailed Description of the Embodiments Section. Episode 15

In this episode, I’m going through the section of the patent application called the detailed description of the embodiments.

Why the Detailed Description Matters

In my approach to drafting patent applications, this is the third section I write, after the claims and then the drawings. The drawings and the detailed description go hand in hand, so it’s useful to have at least sketches before describing your embodiments.

The detailed description of the embodiments is the most important section at the time of filing because while claims can be changed after filing, they can only be changed if support exists in the rest of the application. New subject matter cannot be added after filing. Most of the substance of your invention will be found in the detailed description.

If you discussed a feature in this section, you can later modify claims to include it. However, if a feature was never mentioned, you cannot add it later—you would have to file a new application.

This is why a thorough detailed description is crucial—it’s often the longest section of any patent application.

Avoid Calling It "The Invention"

I use the term "embodiments" rather than "detailed description of the invention." Avoid referring to embodiments as "the invention" because an invention is an idea, while embodiments are ways to achieve the idea—different examples or versions of your invention.

For example, if you invent a new avocado slicer with five blades:

• ✅ It’s fine to say: "In one embodiment, there are five blades."

• ❌ Do not say: "The invention has five blades."

If you state that "the invention" has five blades, then someone making a slicer with four blades might argue that they aren’t infringing because you limited your invention to five blades.

While legally, a well-drafted claim (e.g., "comprising a plurality of blades") should cover multiple configurations, a judge might misinterpret your description. Courts tend to infer intent from the detailed description, even though they should not read limitations from a single embodiment into the claims without clear intent from the applicant.

To avoid this risk, always describe multiple embodiments.

Describe Multiple Embodiments

If you only describe one embodiment, a court may interpret that as your entire invention.

To prevent this, provide alternative embodiments. For example, if your avocado slicer has five blades, also include:

• "Other embodiments may have 2, 3, 4, 6, or more blades."

• "One blade may also work."

When drafting, think about different versions someone might create by removing parts, replacing parts, or adding features. Include these variations as alternative embodiments.

How to Structure the Detailed Description

If you have drawings, the easiest way to draft this section is to go figure by figure and describe:

1. Every part

2. How they connect

3. The purpose of each part

4. How the invention works and solves a problem

If you listened to the previous episode on patent drawings, you’ll remember that each part has a reference number. Every time you mention a part in the detailed description, follow it with its reference number.

For example, if describing a bicycle, with:

• The bicycle itself labeled 2

• The wheels labeled 4

• The frame labeled 6

• The chain labeled 8

• The pedals labeled 10

You might write:

"The bicycle 2 has at least two wheels 4, connected through a frame 6. Pedals 10 are connected to at least one of the wheels 4 by a chain 8."

If two parts are similar (e.g., two wheels), you can label them 4a and 4b and refer to them as "first wheel 4a" and "second wheel 4b."

Three Requirements for the Detailed Description

1. Written Description Requirement

   • You must convey to the public what you claim is your invention.

   • There must be enough detail for a person skilled in the art to reasonably conclude you had possession of the invention.

   • A physical prototype is not required—you just need to describe the invention fully using words, drawings, or formulas.

2. Enablement Requirement

   • You must describe your invention clearly enough that someone skilled in the art could make and use it.

   • The patent must provide enough information so that after 20 years, others can reproduce your invention.

3. Best Mode Requirement

   • You must disclose the best version of your invention that you know at the time of filing.

   • You don’t need to explicitly label it as "preferred", but you must describe it.

   • If you try to hide the best mode, you could risk invalidation later.

Note: While best mode is legally required, failure to include it does not invalidate a patent, though it may lead to rejection during examination.

Using Consistent Terminology

Your claims and detailed description must use consistent terminology to avoid Section 112 rejections.

For example, if your claims state:

"A bicycle comprising at least two rolling members."

Then, in the detailed description, you must include:

"In some embodiments, the rolling member may be a wheel, a cylinder, and can be made of rubber, wood, or metal."

If you fail to define "rolling member" in your description, an examiner may issue a Section 112 rejection for lack of written description support.

Final Steps

After drafting the detailed description, you may realize your claims should be adjusted—that’s fine! Patent drafting is an iterative process.

Before finalizing, ensure:

• Every term in your claims appears in the detailed description.

• All features in the drawings are fully described.

• Multiple embodiments are included for flexibility.

• Your description supports enablement and written description requirements.

• Your best mode is disclosed.

Final Thoughts

If you need help drafting your patent application and drawings, I offer these services through my practice at Diament Patent Law.

In the next episode, I’ll cover a short section called "Brief Description of the Drawings."

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