Joint Ownership of Patents: 6 Essential Rules for 2026

Two companies co-develop a technology. Both contribute inventors, both go on the patent, and everyone shakes hands. Eighteen months later one of them licenses your fiercest competitor, keeps every dollar, owes you no accounting, and is entirely within its rights. Nothing was breached, because nothing was written. That is the default rule of joint ownership of patents in the United States, and it surprises sophisticated parties every year. The statute that produces this outcome is one sentence long.

What Joint Ownership of Patents Means Under Section 262

The governing text is 35 U.S.C. § 262, and it reads in full: “In the absence of any agreement to the contrary, each of the joint owners of a patent may make, use, offer to sell, or sell the patented invention within the United States, or import the patented invention into the United States, without the consent of and without accounting to the other owners.”

Read the two halves carefully, because each one gives something away. Without the consent of means no co-owner needs your permission. Without accounting to means no co-owner owes you a share of what it earns. The section dates to the 1952 Patent Act and was amended in 1994 to add offers to sell and importation, aligning it with the rights granted elsewhere in the Act.

The opening clause is the escape hatch, and most parties never use it. “In the absence of any agreement to the contrary” means every rule below is a default, not a mandate. Co-ownership is what you get when nobody negotiated; it is rarely what anybody actually wanted.

Note what the statute does not do. It says nothing about who prosecutes the application, who pays maintenance fees, who controls enforcement, or what happens if a co-owner sells its interest. Those gaps are filled by case law that is, on balance, unfriendly to whichever owner assumed it was in charge.

Rule 1: Every Co-Owner Can Practice the Patent for Free

Each co-owner may make, use, offer to sell, sell, and import the invention. No permission. No royalty. No notice. Your co-owner can compete against you using the very patent you paid to prosecute, and the patent gives you no cause of action, because you cannot infringe something you own.

There is a second-order consequence that catches people. Because ownership percentage is irrelevant to the statute, a co-owner holding a sliver has precisely the rights of one holding almost everything. The math of the cap table does not carry over to the patent. A one percent owner and a ninety-nine percent owner have identical statutory rights.

Rule 2: Any Co-Owner Can License Your Competitor

The statute lists practicing rights, and the Federal Circuit has read it to carry the licensing right along with them. A co-owner may grant a license to anyone, on any terms, without consulting you and without sharing the proceeds. This is the provision that converts a friendly co-development into a strategic problem.

It also works retroactively in a way that can end litigation you have already filed. In Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456 (Fed. Cir. 1998), a co-inventor who had been added to the patent granted the accused infringer a retroactive license. The suit did not survive it. A defendant that finds an unhappy co-owner has found a settlement it can buy cheaply, and you will not be consulted on the price.

If your commercial plan depends on being the only source, co-ownership is structurally incompatible with it. That should be settled before filing, not after — the same discipline that makes an invention assignment agreement worth getting right on day one.

Rule 3: You Cannot Sue Without Every Co-Owner

Here is the trap that turns an inconvenience into a dead end. All co-owners must join an infringement action as plaintiffs. And a co-owner who prefers not to sue cannot be dragged in.

Schering Corp. v. Roussel-UCLAF SA, 104 F.3d 341 (Fed. Cir. 1997), confirmed that one co-owner may impede another’s ability to sue simply by refusing to join. The Federal Circuit closed the obvious workaround in STC.UNM v. Intel Corp., 754 F.3d 940 (Fed. Cir. 2014), holding that a co-owner’s substantive right to refuse defeats involuntary joinder under Rule 19. Procedure gives way to the substantive right.

Put those together and the picture is stark. A single holdout — including one your adversary has just licensed — can make your patent unenforceable in practice while leaving it perfectly valid on paper. An unenforceable patent is a curious asset: it still deters the uninformed and still costs maintenance fees.

Rule 4: One Claim Is Enough to Own the Whole Patent

Co-ownership does not arrive in proportion to contribution. Under Ethicon, a person who is a co-inventor of even a single claim is, absent an assignment, a co-owner of the entire patent — every claim of it, including claims they had nothing to do with.

This is why inventorship disputes are ownership disputes wearing a disguise, and why an omitted inventor is a live risk rather than a paperwork error. A defendant with a plausible story about an uncredited contributor is not merely attacking validity; it is shopping for a co-owner who can license it. The mechanics of who qualifies are covered in our guide to joint inventorship rights and responsibilities.

The defensive move is unglamorous and effective: get assignments signed by everyone who touched the conception, including contractors and consultants, before the application is filed. An assignment converts a potential co-owner into an employee with no leverage.

Rule 5: True Exclusive Licenses Become Nearly Impossible

Think about what you are actually promising when you grant exclusivity. You are promising the licensee that nobody else will be licensed. You cannot make that promise on a jointly owned patent, because your co-owner retains an independent right to license anyone it likes.

So the exclusive license you sign is exclusive only as to your own interest. If your co-owner licenses the same field tomorrow, your licensee has lost the thing it paid for, and it will look to you rather than to the statute. In practice the only route to genuine exclusivity is unanimity: every co-owner agrees not to grant further licenses and not to practice the invention themselves.

• What you can grant alone: a non-exclusive license under your own interest.
• What you cannot grant alone: exclusivity, because you do not control your co-owner’s rights.
• What your licensee will assume: that “exclusive” means exclusive. Disclose the co-ownership.
• What fixes it: a written agreement binding every co-owner before the deal is signed.

Rule 6: Contract Around Section 262 Before the Invention Exists

Every default above yields to “any agreement to the contrary.” The statute invites you to override it, and the leverage to do so exists only while both parties still want the deal. After the technology has value and the relationship has cooled, nobody signs away a right the statute already handed them for free.

The instrument is usually a joint development agreement or a co-ownership agreement executed at the start of the collaboration. Some parties avoid the problem entirely by assigning all rights into a single entity — one owner, one decision-maker — and licensing each participant back. That is cleaner than it sounds and eliminates the enforcement trap altogether.

1. Consent to license: require written consent before any co-owner licenses a third party.
2. Accounting: override the no-accounting default and fix the revenue split in numbers.
3. Enforcement: obligate every co-owner to join suits, and say who funds and controls them.
4. Prosecution and fees: name who drafts, who decides on continuations, and who pays maintenance.
5. Transfer: restrict assignment of a co-owner’s interest, with a right of first refusal.
6. Exit: decide in advance what a deadlock or a departure does to the patent.

None of this is exotic drafting. It is a short document that has to exist before it is needed, which is precisely why it so often doesn’t.

How PerspireIP Can Help

We help companies see co-ownership coming — auditing inventorship before filing, structuring joint development so Section 262’s defaults never apply, and untangling portfolios where a co-owner already holds a veto. If you are entering a collaboration or have just discovered a co-owner you didn’t plan for, contact our team and we will map the exposure.

This article is general information, not legal advice; consult a qualified attorney for your situation.

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