Claim Drafting (Part 4) - Independent and Dependent Claims. Episode 12

Recap of Previous Claim Drafting Episodes

So far, I’ve talked about several important aspects of claim drafting:

1. Identifying Your Invention – Understanding what your invention actually is before writing claims.

2. Drafting Device or Apparatus Claims – How to write claims for physical inventions.

3. Drafting Method Claims – How to write claims for new and non-obvious methods.

In this episode, I’m going to go through independent and dependent claims—how they function and why they are essential in patent drafting.

Independent vs. Dependent Claims

If you’ve looked through any of the patents I’ve referenced before and gone to the claims section, you’ll see that it’s common for patents to have around 20 claims. This is because the patent office charges additional fees if you include more than 20 claims. The patent office also charges extra fees if you have more than three independent claims, so a general practice is to draft three independent claims and 17 dependent claims—but this is not a hard and fast rule.

What Are Independent and Dependent Claims?

• Independent Claims – These stand alone and do not reference any other claim. They define the broadest scope of your invention that you believe should be protected.

• Dependent Claims – These reference an independent claim and narrow its scope. They serve as backups in case the independent claim is found invalid.

Example: A Flying Bicycle

Let’s say you invented a flying bicycle that operates through pedal power. However, for some reason, you thought you had actually invented the regular bicycle itself.

You start thinking of all the parts:

• A frame

• Wheels

• Handlebars

• Pedals

• A chain connecting the pedals to the wheels

• Wings attached to the frame

• A rudder

Since you thought you had invented the bicycle, you want to get patent protection for all bicycles. You might draft an independent claim like this:

Example of an Independent Claim:

1. I claim a device for transporting a person, the device comprising:

• A frame,

• A plurality of wheels attached to the frame,

• At least one pedal,

• A chain connecting the pedal to the plurality of wheels so that when the pedal rotates, the chain causes the plurality of wheels to rotate, and

• A handlebar connected to the frame to steer the device.

This is a simplified claim just to illustrate the major elements of bicycles that might be in a claim for a generic bicycle.

Now let’s say the patent examiner looks at your claim and, for whatever reason, also has never seen a bicycle before, and grants you a patent. You’re excited to have a patent for the bicycle.

Later, you find out that a company is making flying bicycles, so you decide to sue them for infringement. Their flying bicycle contains:

• A frame

• Wheels

• Pedals

• A chain

• A handlebar

You take them to court, but the bicycle maker argues that bicycles have existed for over a hundred years, meaning your patent should have never been granted. They provide evidence of prior bicycles, and the judge invalidates your patent.

Now, you have nothing because you never claimed wings. You didn’t claim wings because you thought your invention was broader than just a flying bicycle.

The Role of Dependent Claims

What could you have done differently?

This is where dependent claims come in. Dependent claims act as backups in case your independent claim is found invalid for not being novel or non-obvious.

You should have included an extra claim beyond the broad one, such as:

Example of a Dependent Claim:

2. The device of Claim 1, further comprising wings attached to the frame.

If you had included this dependent claim, even if your broad bicycle claim was found invalid, the judge might have said:

“The claim for a basic bicycle is invalid, but your claim for a bicycle with wings is novel and non-obvious.”

At that point, the flying bicycle manufacturer would still infringe your dependent claim. That’s why it’s generally a good idea to have dependent claims, as you never know if your broad claims might be found invalid, requiring you to rely on narrower claims for legal protection.

The Benefits of Dependent Claims

Instead of rewriting the entire independent claim with added limitations, dependent claims allow you to build on previous claims by adding specific features.

This saves time and reduces cost because:

• The patent office charges extra fees for more than three independent claims.

• You are allowed 20 total claims, so it’s strategic to have a few broad independent claims and many dependent claims covering specific features.

• If your broad claim is invalid, dependent claims still provide protection.

Example of a Second Dependent Claim:

3. The device of Claim 2, further comprising a rudder attached to the frame.

This further narrows the invention but keeps you protected.

Dependent Claims for Method Patents

You can also write dependent claims for method patents.

For example, in the last episode, I discussed a method for making guacamole. You can find the patent using Google Patents for U.S. Patent 5,871,794.

• The independent method claim (Claim 10) describes:

1. Removing the skin and pit from an avocado

2. Removing the husk and seeds from a tomatillo to obtain tomatillo pulp

3. Mixing the avocado and tomatillo pulp together

4. Heating the mixture to 85°C for about 10 minutes

• The dependent claim (Claim 11) states:

11. The process of Claim 10, further comprising the steps of washing, scalding, and pressing the tomatillo pulp prior to removing the seeds and outer skin.

Why is this important?

• If Claim 10 is invalid, Claim 11 could still be found valid and enforceable.

• Dependent claims allow for fallback protection and increase the chances of some part of your invention being patentable.

At some point, your claim may become so narrow that it’s easy for competitors to design around it, so having a balance of broad and narrow claims is essential.

Additional Benefits of Dependent Claims

While the main reason for dependent claims is to serve as legal backups, there are additional advantages:

• Easier amendments – If your broad independent claim is rejected, you already have narrower claims that the examiner can review.

• Clarification of different embodiments – Helps illustrate variations of your invention.

• Simplifies litigation – Juries can more easily understand detailed dependent claims.

Final Thoughts

There could be hundreds of episodes on claim drafting techniques, but at some point, you need to start drafting the rest of your application.

The next episode will be the final episode specifically on claim drafting—covering the Top 10 Tips for Claim Drafting to help you avoid common mistakes.

I’ll also revisit claim drafting when discussing responding to patent rejections.

Need Help with Patent Drafting?

If you want help drafting your patent application and claims, I offer these services through my practice at Diament Patent Law. I’m Adam Diament, and until next time, keep on inventing!