Economic, Commercial and Intellectual Property Laws · Law relating to Patents

Rights, Ownership and Co-owners of Patents under Section 50

Updated 11 October 2026 · Fact-checked

A patent can be granted to two or more persons. Under section 50, unless an agreement says otherwise, each co-owner has an equal undivided share and may work the patent for his own benefit without accounting to the others. But no licence can be granted, and no share assigned, without every co-owner's consent.

Understand Rights, Ownership and Co-owners of Patents

A patent is a right granted for an invention. Under section 48, it lets the patentee stop others who lack consent from certain acts. For a product patent, these acts are making, using, offering for sale, selling or importing the product for those purposes in India. For a process patent, they are using the process, and using, offering for sale, selling or importing the product obtained directly by that process.

The patent runs for a limited time. Under section 53(1), the term is twenty years from the date of filing of the application. For PCT international applications designating India, it is twenty years from the international filing date. The patent ceases if the renewal fee is not paid within the prescribed period or the extended period allowed. After expiry or cessation, section 53(4) says the subject matter gets no protection.

A patent can be owned by more than one person. Section 50 deals with this. It sets default rules that apply unless the co-owners have made an agreement to the contrary. The agreement always comes first.

The default rules balance two things. Each co-owner is free to work the invention himself. But the patent as an asset (licensing it or assigning a share) needs everyone's agreement. This protects each co-owner from having a stranger brought in without consent.

Section 70 gives the registered grantee or proprietor power to assign, license or otherwise deal with the patent. This power is subject to the co-ownership rules and to rights of others that are entered in the register. So with co-owners, section 50 limits section 70.

Key rules to remember

Equal share (s. 50(1)): Patent granted to 2 or more persons → equal undivided shares, unless agreement to the contrary; The agreement can change the shares. Without one, shares are equal, not in proportion to contribution.
Working the patent (s. 50(2)): Each registered co-owner may, by himself or his agents, exercise the s. 48 rights for his own benefit without accounting to the others; Subject to s. 50 and s. 51, and unless an agreement says otherwise.
Licence or assignment (s. 50(3)): Licence not granted and share not assigned by one co-owner except with consent of the other(s); Subject to any agreement in force. This is the most tested point.
Sale of patented article (s. 50(4)): Purchaser from one co-owner deals with the article as if bought from a sole patentee; The buyer need not check the other co-owners' consent.
Rights of patentee (s. 48): Product: prevent making, using, offering for sale, selling, importing. Process: prevent using the process, and using, offering for sale, selling, importing the product directly obtained; Exclusive right to prevent third parties without consent, in India.
Term (s. 53(1)): 20 years from date of filing of the application (PCT: from international filing date); The term runs from filing, not from grant.
Patent of addition (s. 55): Term = term of main patent, or the unexpired part; no renewal fees; If the main patent is revoked, the court or Controller may on request make it an independent patent for the remaining term, and then renewal fees become payable.

How to solve Rights, Ownership and Co-owners of Patents questions

Use this order for any question on patentee's rights, term or co-owners.

1Identify what is asked: rights, term, renewal, or dealing (licence, assignment, sale) by a co-owner.
2Check whether there is a co-owner agreement. Section 50 rules apply only if there is no agreement to the contrary.
3If the act is working the invention for own benefit, apply section 50(2): allowed, with no accounting to the others.
4If the act is granting a licence or assigning a share, apply section 50(3): consent of the other co-owners is required.
5If an article was sold by one co-owner, apply section 50(4): the buyer is protected as if from a sole patentee.
6For term questions, apply section 53: twenty years from filing, and cessation on non-payment of renewal fee.
7Write the conclusion clearly: the act is valid or not, and why.

Quickest way: Agreement, Use, Consent

When to use it: For short case-based questions on co-owners with limited time.

Agreement? If yes, it governs. If no, apply defaults.
Use by self: free, no accounting (s. 50(2)).
Licence or assignment: needs consent of all (s. 50(3)).
Sale of article: buyer is safe (s. 50(4)).
State the section and a one-line conclusion.

Common mistakes in Rights, Ownership and Co-owners of Patents

Saying a co-owner can license the patent alone because he owns a share.
Students mix up working the patent with dealing in it.
Fix: Remember: working for own benefit is free; licence or assignment needs consent under section 50(3).
Saying a co-owner must share profits from his own working of the patent.
Students assume partnership-type rules apply.
Fix: Section 50(2) says he need not account to the others, unless an agreement says otherwise.
Ignoring the agreement to the contrary.
Students learn the default rules and forget they are only defaults.
Fix: Begin every co-owner answer by checking for an agreement.
Stating the term as twenty years from the date of grant.
Confusion with the grant date.
Fix: Section 53(1): twenty years from the date of filing; for PCT, from the international filing date.
Saying a buyer of a patented article from one co-owner can be sued by the other co-owners.
Students forget section 50(4).
Fix: The buyer and those claiming through him deal with the article as if sold by a sole patentee.
Saying a patent of addition needs its own renewal fees and has its own twenty-year term.
Treating it as an independent patent.
Fix: Under section 55, its term matches the main patent's, and no renewal fees are payable unless it becomes independent.

Worked examples

Example 1

A and B are registered joint patentees of a patent for a water purifier. There is no agreement between them. A grants a licence to C to manufacture the purifier without B's consent. B objects. Examine whether the licence is valid.

Show the solution

Provision: section 50(3) says that, subject to section 50, section 51 and any agreement in force, where two or more persons are registered as grantee or proprietor, a licence under the patent shall not be granted except with the consent of the other person or persons.
Facts: A and B are registered co-owners. No agreement exists. A granted a licence to C without B's consent.
Section 70 gives registered proprietors the power to license, but it is expressly subject to the co-ownership provisions, so it does not rescue A.
Conclusion: the licence cannot be granted without B's consent, so A's grant to C is not in accordance with section 50(3).

Answer: A cannot validly grant the licence to C without B's consent. Section 50(3) requires the consent of the other co-owner, and there is no agreement to the contrary.

Example 2

X and Y are co-owners of a patent for a machine part, with no agreement. X manufactures and sells the part himself and keeps all the profit. Y demands a share of the profit. Z buys a part from X and resells it. Advise X, Y and Z.

Show the solution

Share: under section 50(1), X and Y each hold an equal undivided share, as there is no agreement.
X's working: section 50(2) allows each co-owner, by himself or his agents, to exercise the section 48 rights for his own benefit without accounting to the other.
Y's demand: because X need not account, Y has no right to a share of X's profit from his own working, unless an agreement says otherwise.
Z's position: section 50(4) says that when a patented article is sold by one co-owner, the purchaser and anyone claiming through him may deal with the article as if sold by a sole patentee. So Z can resell it.
Limit: X could not license a third party or assign his share without Y's consent (section 50(3)).

Answer: X may work the patent and keep the profit, so Y's demand fails. Z may freely deal with and resell the part. Only licensing or assigning a share would need Y's consent.

Exam tips

Write the section number with every point: 50(1) shares, 50(2) working, 50(3) consent, 50(4) buyer.
Always mention 'unless an agreement to the contrary is in force'.
For term questions, state twenty years from filing and the PCT variation.
Case questions are usually about one co-owner licensing or assigning. Answer: consent is needed.
End each answer with a clear one-line conclusion.

Practice questions from Law relating to Patents

Rights, Ownership and Co-owners of Patents in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

CS ProfessionalRights of Co-owners of Patents

Rights, Ownership and Co-owners of Patents: frequently asked questions

What does section 50 of the Patents Act say about co-owners?

It says co-owners hold equal undivided shares unless there is an agreement otherwise. Each may work the patent for his own benefit without accounting to the others. A licence or assignment of a share needs the consent of the other co-owners.

What is the term of a patent in India?

Under section 53(1), it is twenty years from the date of filing of the application. For PCT applications designating India, it is twenty years from the international filing date. The patent ceases if the renewal fee is not paid in time.

Can one co-owner sell his share in a patent alone?

Not without consent. Section 50(3) bars the assignment of a share by one co-owner except with the consent of the others, subject to any agreement in force.

What happens to the patented article sold by one co-owner?

Under section 50(4), the buyer and anyone claiming through him can deal with the article as if it had been sold by a sole patentee.