How to Handle a Double Patenting Rejection. Episode 60

What Is Double Patenting?

In this episode, I’m going to talk about something called double patenting. It may sound complicated, but for the most part, it is not as tricky as the legal language makes it seem. The basic rule, which makes sense, is that you are not allowed to get two different patents for the same invention.

But why would an inventor even want two patents for the same invention? And why would it even be possible for that to happen?

Why Would You Want Two Patents for the Same Invention?

The reason an inventor might want two patents for the same invention has to do with how long a patent lasts, which is generally 20 years from the original filing date.

For example, if I filed an application on January 1, 2018, my patent would last until January 1, 2038. But if I filed another application for the same invention a year later, on January 1, 2019, and that second patent issued, it would last until 2039. This means I could get 21 years of protection instead of 20, which is an unfair extension.

To prevent this, the Patent Office enforces the one patent per invention rule.

How Does This Happen?

You might be wondering why someone would file two applications for the same thing. It’s usually not because an inventor intentionally submits two identical applications. What typically happens is that an inventor files a continuation application—which I discussed in a previous episode.

Your continuation application may have claims that are similar or even identical to those in your first application. If your continuation application contains identical claims, you will receive what is called a same-invention or statutory double patenting rejection.

Statutory Double Patenting Rejection

A statutory double patenting rejection means you are never allowed to get a second patent on the exact same invention. There is nothing you can do to overcome this, except by amending your claims so they are not identical to your first application.

If you believe your claims are not actually identical, you can argue with the examiner and try to convince them that the rejection is incorrect. However, it is rare for an inventor to make the mistake of filing two applications with identical claims.

Obviousness-Type Double Patenting Rejection

A more common issue arises when you file a continuation application and get claims that are very similar to your first application—so similar that the second set of claims are really just obvious variations of your first patent. This results in what is called an obviousness-type double patenting rejection, also known as a non-statutory double patenting rejection.

Even though the inventions are not exactly the same, the Patent Office does not want inventors to extend the life of a patent by separately patenting every slight variation. If this happens, you will receive a double patenting rejection.

Why This Used to Be a Bigger Issue

Double patenting used to be a much bigger issue because of the way patent terms were calculated before 1995. Before 1995, patents lasted 17 years from the date of issuance, rather than 20 years from the filing date.

For example, if your first patent issued in 2020, it would last until 2037 (17 years). If you obtained a second patent for an obvious variation in 2025, that second patent would last until 2042—giving you extra years of patent protection for essentially the same invention.

Because of this, some inventors gamed the system by making minor tweaks, filing new applications, and extending the protection of their inventions beyond the intended 17 years.

Why This Is Less of an Issue Now

Since 1995, patent terms are now based on the filing date, not the issuance date. This means that all patents that claim priority to an earlier application expire 20 years from the earliest filing date.

So now, there is no longer a way to extend the patent term simply by filing continuation applications with minor variations.

However, you can still receive an obviousness-type double patenting rejection. The good news is that these are easy to handle.

How to Handle an Obviousness-Type Double Patenting Rejection

If you receive an obviousness-type double patenting rejection, the easiest way to fix it is by filing a terminal disclaimer. The examiner will often state that your patent will be allowed if you file a terminal disclaimer.

A terminal disclaimer means you are giving up any portion of the patent term that would extend beyond the expiration date of your first patent.

Why Terminal Disclaimers Matter

Even though a terminal disclaimer does not actually change anything—because both patents were already set to expire on the same date—it serves another important purpose.

A terminal disclaimer requires that all patents connected by the disclaimer must be owned by the same entity.

Why Does Ownership Matter?

The reason for this requirement is to prevent an inventor from getting a patent on one invention and then selling a continuation patent—which is just an obvious variation of the first—to a different company.

Why is this a problem? Imagine a competitor is accused of patent infringement and finds out that two different companies each own patents for nearly the same invention. The competitor could be sued by both companies for essentially the same thing. To prevent this, the Patent Office requires that terminally disclaimed patents remain under the same ownership.

Practical Considerations for Terminal Disclaimers

Most of the time, a terminal disclaimer is not a big deal because the owner of one patent is usually the same owner of the other patent. However, problems can arise if the patents are later split up and sold to different entities. In such cases, enforcement may become complicated if ownership rules are not followed.

When Might You Want to Fight an Obviousness-Type Double Patenting Rejection?

Although filing a terminal disclaimer is usually routine, there may be strategic reasons to fight an obviousness-type double patenting rejection. For example, if you want to sell different patent rights to different entities, you may prefer not to link them through a terminal disclaimer.

However, for most standard situations, filing a terminal disclaimer and ensuring that all related patents remain under the same ownership is the best approach.

If you follow these steps, both of your similar patents will expire at the same time, which is generally 20 years from the filing date of the first application.

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