Can I Use a Provisional Patent Application to Stop Infringers or to Stop Someone From Stealing My Invention? Episode 112

A Common Question in Inventor Forums

I’m in several online inventor groups where people ask questions and others post answers. Often, there’s bad advice floating around—because, surprise—people on the internet don’t always know what they’re talking about. In this episode, I’m going to go over a specific question I came across and walk through the correct answer.

Here’s the question:

“If you come up with an idea that is easy to knock off, would it be worth filing a provisional patent application and then letting it expire, but not filing for the patent? That way, at least someone trying to rip you off doesn’t have the chance to file a patent on it and go after you for infringing in the future. Assume you wouldn’t have the funds to sue for infringement if you were to own the patent.”

What Is a Provisional Patent Application?

Let’s break this question down step by step. A provisional patent application is a type of patent application that never becomes a patent by itself. If you file one, you have 12 months to file a real, or non-provisional, patent application. If you do file the non-provisional application within that time, it’s treated as if it was filed on the date of the earlier provisional.

There are lots of caveats here, so make sure to listen to my episodes specifically on provisional patent applications. If you don’t file anything within 12 months, it’s as if the provisional never existed. It doesn’t get published, and it doesn’t get examined. It just disappears.

Can a Provisional Application Stop Infringement?

The first part of the question asks if filing a provisional application stops others from making your product. The answer is: no.

You can’t even stop someone from making your product if you have a non-provisional patent application. You can only legally stop someone from making or using your invention if you have an issued patent. Until that point, you can’t sue for damages or injunctions.

What you can do is label your product “patent pending,” which might scare off a few people who fear a future patent will issue. You can also send a warning letter to a party making your product, informing them that a patent application is pending and that if a patent is granted, they may be liable for damages dating back to when they were notified.

There are all kinds of rules about when back damages can be awarded, but it is possible to get damages going back before your patent actually issues. So, realistically, sending a warning letter and putting “patent pending” on your product are the only things you can do while your application—provisional or non-provisional—is pending.

Can Someone Else File a Patent After Your Provisional?

Now let’s look at the second part of the question: what happens if someone files a patent application after you’ve filed a provisional?

If you file a provisional and then start selling your invention or make it public, those disclosures won’t be held against your own future patent application, as long as you file the non-provisional within 12 months. But those grace periods don’t apply to other people.

If someone else independently comes up with the same invention—even if they didn’t copy you—and you had already made your invention public before they filed, then they can’t get a patent. Your public disclosure has made it prior art.

What If You Never Made It Public?

Let’s say you filed a provisional patent application but never made your invention public. Then someone else independently files a patent application for the same invention.

Are they allowed to do that?

It depends. If they truly came up with the invention on their own and didn’t copy it from you, then yes, they can get a patent. Since your provisional wasn’t published, it can’t be used as prior art to reject their application.

Provisional patent applications aren’t published, so unless you later file a non-provisional application and it gets published, your provisional is essentially invisible.

What If Someone Steals Your Idea?

Now, what if someone did steal your idea and filed a patent application? Are they allowed to do that?

No, they’re not. Only inventors can file patent applications.

When you file, you must sign a declaration stating that you are the inventor. If you lie, that’s a serious offense—it can result in fines and up to five years in jail.

If you see someone else’s patent application and you know they stole your idea, you can file what’s called a derivation proceeding. This is handled by the Patent Trial and Appeal Board. It’s like a mini-trial where you submit evidence to show that their invention was derived from yours. If successful, you can be listed on the patent instead of them.

There are other things you can do, but that’s the primary route.

What If You Let Your Provisional Expire?

Here’s another scenario. You came up with an idea, filed a provisional application, but let it expire—or maybe you never filed anything at all. Later, someone else comes along, independently comes up with the same idea, and files a patent application and gets a patent.

Can they sue you for infringement?

Even if you can prove that you came up with the idea first—say, by retrieving the filed provisional from the Patent Office—you might not be able to invalidate their patent. But can they go after you?

This question has come up in real-world situations—especially for companies that rely on trade secrets instead of patents. What happens if another company later patents the same technology?

The Prior User Rights Defense

Today, the general rule is: you cannot be sued if you are a prior user—even if you never filed a patent. This is called the prior user rights defense.

There are several caveats. You have to show that you were using the invention more than one year before the other party filed their application—or before they made a public disclosure of it. The rule is found in 35 U.S.C. § 273, part of the America Invents Act.

Proving Prior Use

How do you prove prior use? Well, a provisional patent application filed with the Patent Office might help.

You’ve probably heard of the so-called “poor man’s patent”—mailing something to yourself to prove you invented it. Don’t do that. But in some ways, a provisional application serves a similar purpose.

For $75 or $150, you can file a provisional and have official evidence that you thought of something—even if the application later goes abandoned.

Technically, under the statute, the prior use defense applies to commercial use, and filing a provisional isn’t proof of commercial use. It just shows you conceived the idea. So, it might not be good enough by itself—but it’s still strong evidence that could help show you were using the invention before the other party filed their application.

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