Patenting for Inventors Ep.165: Help! My Co-Inventor Refuses to Sign the Patent Application!

You've got a strong invention and a patent application ready to file. There's just one problem: your co-inventor won't sign. Maybe they're ghosting you. Maybe they're convinced signing something will cost them their stake. Maybe the relationship just fell apart. Whatever the reason, a non-cooperative co-inventor is one of the most frustrating — and surprisingly common — situations inventors face.

In Episode 165 of Patenting for Inventors, Nolan Heimann partner and registered patent attorney Adam Diament walks through exactly what the law allows you to do when a co-inventor refuses to cooperate. At the center of it is a formal procedure called the substitute statement, governed by 37 CFR 1.64, which allows applicants to move forward with a patent filing when a named inventor won't sign the standard declaration — provided you can demonstrate a good-faith effort to obtain that signature.

But the episode goes further than procedure. Adam clarifies what co-inventorship actually means legally — because not everyone who contributed an idea over a brainstorming session qualifies — and explains why getting this right matters enormously. Listing the wrong inventors, or intentionally omitting a true co-inventor, can be grounds for invalidating an entire patent under a doctrine known as inequitable conduct.

He also addresses one of the most common points of confusion: the difference between inventorship and ownership. Signing a declaration doesn't transfer rights — it simply confirms who contributed to the invention. Ownership, assignments, and profit-sharing are governed by separate agreements. Understanding that distinction can defuse a surprising number of disputes before they escalate.

For startup founders in particular, this episode is essential listening. When co-founders brainstorm together, roles blur, people leave, and months later — when the patent finally gets filed — someone who's no longer involved suddenly wants leverage. Adam explains how the law provides a path forward, and more importantly, how good documentation from the start can prevent the problem entirely.

Patenting for Inventors Ep. 165:

Podcast Transcript:

Hello, and welcome to the Patenting for Inventors podcast. I’m your host, Adam Diament, a registered patent attorney and partner at the law firm of Nolan Heimann in Los Angeles, California. This episode is “Help! My Co-inventor Refuses to Sign the Patent Application?” 

So picture this. You’ve come up with a killer invention, maybe a new type of foldable drone that transforms into a pair of sunglasses. It’s awesome. You’re pumped. You want to file a patent application. But wait. That one friend who helped brainstorm the power mechanism over pizza one night? You realize they might technically be a co-inventor. And now they’re ghosting you. Or worse, they’re flat out saying they won’t sign anything. What now? 

Look, this happens more often than you’d think. Sometimes it’s a falling out. Sometimes someone just doesn’t understand what they’re being asked to sign. Or they think they’re about to get scammed out of a billion-dollar idea. Or they’re just being difficult for no real reason. Whatever the case, here’s the thing. If someone is truly a co-inventor, and we’ll come back to what that really means, you can’t just cut them out of the process. But also, they can’t hold your patent hostage either. 

Let’s take a quick breath and look at how this works legally. When you file a patent application, normally everyone who’s listed as an inventor has to sign what’s called a declaration. It basically says, yes, I’m an inventor of what’s in this application, and I authorize the USPTO to process it. It’s a formality, but an important one. But what happens if one of those inventors won’t sign it? 

The good news is there’s actually a procedure baked right into the patent rules for this exact situation. So if you’re filing a U.S. patent application and one of the inventors won’t cooperate, you don’t have to scrap the whole thing. You can still move forward. But, and this is important, you have to prove that you made a real effort to get that signature. It’s not like you can just say, “Eh, I didn’t feel like calling them.” 

What you’ll usually do is file what’s called a substitute statement. It’s basically a sworn declaration that says, “We tried, they refused or we couldn’t reach them, here’s how.” You’d need to show that you tried in good faith, maybe you emailed, called, sent letters, whatever. And you attach all of that to your filing. The USPTO doesn’t want people skipping inventors lightly, but they also don’t want one person to block progress for everyone else. 

Now, let’s rewind a second because I mentioned something earlier that matters big time here. What exactly is a “co-inventor”? Just because someone gave you a cool idea over lunch doesn’t automatically make them a co-inventor. You’ve got to be careful about who you list. A co-inventor is someone who contributed to at least one claim of the invention. Not just background brainstorming, not just “hey, wouldn’t it be cool if,” but actual conception of a claim-worthy element. If someone didn’t contribute to the specific subject matter being claimed, they’re not a co-inventor. That’s a legal line you really want to get right. Too many inventors is bad, and too few is worse. 

But if they are a true co-inventor and they’re just refusing to play ball, that’s where this procedure comes into play. Let’s say you’re working with a patent attorney, hopefully someone like me, and you’ve figured out that the person really does count as a co-inventor. You’ve got the draft application, and now it’s time for signatures. You send them the documents. Nothing. You follow up. Still nothing. Maybe you even get an angry text saying they’re not interested and never to contact them again. At that point, you’re allowed to use the procedures under 37 CFR 1.64. That’s the one that covers the substitute statement for a non-cooperative inventor. 

Now, one thing I get asked a lot is, “Well, what if I just don’t list them at all and hope no one notices?” Yeah, don’t do that. Failing to name a true inventor is grounds for invalidating your entire patent. It’s called inequitable conduct. And if someone later proves that you intentionally left off a co-inventor, not only could the patent get canceled, but you could also run into some pretty ugly legal and ethical issues. So don’t try to play cute with the list of inventors. It’s not worth it. 

Also, let me clear up another thing. Signing the declaration doesn’t mean someone is giving up their rights to the invention. It just means they’re agreeing they’re an inventor. Ownership and inventorship are two totally different beasts. You can be an inventor and not own any rights. You can assign those rights away to a company, or a co-founder, or anyone else. But the declaration? That’s just about telling the truth to the USPTO. So if your co-inventor is worried that signing something will make them lose their stake, you can reassure them. That’s not what the declaration does. 

Another thing that tends to come up in these situations is money, or more specifically, fear of money. A co-inventor sometimes refuses to sign because they think the moment they do, they’re losing leverage. They worry that once the patent is filed, someone else is going to cut them out of future profits. And honestly, that fear isn’t totally irrational if expectations were never discussed up front. But legally, refusing to sign doesn’t actually give them extra power. It just slows things down and creates more paperwork. 

Here’s the part that surprises a lot of people. Even if someone is a co-inventor, that does not automatically mean they get paid. Inventorship is about who contributed to the invention. Ownership is about who owns the patent rights. Those two things are separate. You can be a named inventor and still have zero ownership interest if you assigned your rights away earlier, like in an employment agreement. So sometimes the refusal is really just a misunderstanding of what’s happening. 

Now let’s talk about what happens after the patent issues, because this is where things can get even more awkward. If a co-inventor never assigned their rights, they technically own an undivided interest in the patent. That means they can license it independently, even without the other inventors’ permission. That’s not a hypothetical. That’s real. So if you’re dealing with a co-inventor who’s already being difficult at the signing stage, that’s a big red flag. It’s one reason why getting assignment agreements signed early is so important, way before emotions get involved. 

You might be wondering whether this problem can be avoided entirely. And the answer is yes, most of the time. The best way is to talk about inventorship and ownership early, before filing, before money enters the picture, and definitely before relationships get strained. Clear agreements up front save an incredible amount of pain later. It’s like a prenuptial agreement, but for inventions. Not romantic, but very practical. 

Another common question I hear is whether the USPTO investigates these disputes. And the answer is no, not really. The Patent Office isn’t going to hold hearings about who’s being stubborn or who’s acting unfairly. They just want to know whether the inventors are correctly named and whether the procedural requirements are met. If you follow the rules and submit the substitute statement properly, they’ll process the application. They’re not there to referee personal conflicts. 

That said, just because the USPTO allows you to proceed doesn’t mean the issue disappears forever. A disgruntled co-inventor can still show up later, especially if the invention turns out to be valuable. They might claim they weren’t properly credited or that they were wrongfully excluded from ownership. That’s when things move from patent procedure into contract law and sometimes litigation. So while the substitute statement lets you move forward, it doesn’t magically erase interpersonal problems. 

This is why I always tell inventors to think strategically, not emotionally. If someone is refusing to sign, ask why. Is it confusion? Fear? A genuine dispute over inventorship? Or just a breakdown in communication? Sometimes a short conversation clears everything up. Other times, it doesn’t. But understanding the motivation helps decide the next step. 

Also, just to be clear, refusing to sign does not stop the clock. Patent rights are first to file. Waiting around for someone to calm down can cost you priority. And once priority is gone, it’s gone. So there are moments where moving forward with a substitute statement is not just allowed, it’s necessary. 

One last thing I’ll mention is that this comes up a lot in startup environments. Founders brainstorm together, roles blur, ideas evolve, and then suddenly someone leaves the company. Months later, you’re filing a patent, and now that former founder wants leverage. That’s a very common fact pattern. The law gives you a way through it, but the cleaner solution is still good documentation from day one. 

So if you take one thing away from this episode, it’s this. A co-inventor refusing to sign is a problem, but it’s not a dead end. The patent system anticipated this scenario. There’s a process. It’s manageable. But it’s also a reminder that patents aren’t just technical documents. They’re legal instruments tied to human relationships, and humans are messy. 

That’s it for today’s episode. I’m Adam Diament, and if you need help filing a patent application or other intellectual property, give me a call at 424-281-0162. Until next time, I’m Adam Diament, and keep on inventing!