What is the difference between a patent assignment and a patent license?
A patent assignment and a patent license are both mechanisms for sharing or transferring patent rights, but they differ fundamentally in what is transferred, who owns the patent afterward, and who can independently enforce it in court.
What a patent assignment is
A U.S. patent has the attributes of personal property. A patent assignment is a transfer by a party of all or part of its right, title, and interest in a patent or patent application. Assignments must be made by an instrument in writing.
For a document to qualify as an assignment, it must convey the entirety of the bundle of rights associated with ownership of the patent or application. Upon a valid assignment, the assignee becomes the owner of the patent and has the same rights as the original owner.
The patent owner may sue in federal court to stop infringement and seek financial damages. Because the patent grant runs to the patentee and their assigns, an assignee holds these same enforcement rights as the new owner.
Assignments should be recorded at the USPTO promptly. An unrecorded patent assignment is void as against any subsequent purchaser or mortgagee for valuable consideration, without notice.
What a patent license is
A patent license is a contractual agreement that the patent owner will not sue the licensee for patent infringement if the licensee makes, uses, offers for sale, sells, or imports the claimed invention within the bounds set by the license. Licensing a patent means the patent owner grants permission to exploit the patented invention while the licensor retains property rights over it.
A license transfers a bundle of rights that is less than the entire ownership interest, and those rights may be limited as to time, geographical area, or field of use. A license is not an assignment of the patent, even if the license is an exclusive license.
Exclusive vs. non-exclusive licenses
Licenses fall into two broad categories:
Exclusive license: The patent owner agrees not to grant the same right to any other party within the defined scope. An exclusive license prevents the patent owner from competing with the exclusive licensee as to the geographic region, the length of time, or the field of use set forth in the license agreement. Ownership of the patent, however, remains with the licensor and does not transfer to the licensee.
Non-exclusive license: The patent owner grants the specified rights without restricting itself from granting the same rights to other parties. The licensor may continue to practice the invention itself and may enter into licenses with additional licensees in parallel.
License agreements are also recordable at the USPTO in the public interest, giving third parties notification of equitable interests in the patent.
Who can enforce the patent
A licensee holds rights by contract rather than by title. Only the patent owner, or a party holding title through a valid assignment, may independently bring an infringement action in federal court. Whether and how a licensee may participate in an infringement suit depends on the scope of rights conveyed in the license agreement.
Key differences at a glance
| Dimension | Assignment | License |
|---|---|---|
| What transfers | All (or a defined portion) of ownership interest | Permission to use; less than full ownership |
| Who owns the patent after | Assignee becomes the new owner | Licensor retains ownership |
| Must be in writing | Yes, required by 35 U.S.C. § 261 | Strongly recommended for enforceability |
| Recording at USPTO | Critical; unrecorded assignment is void against later buyers without notice | Recordable; gives third parties public notice of the license interest |
| Can be scoped by territory or field | Yes (partial assignment of a defined portion) | Yes (common in license agreements) |
| Independent right to sue for infringement | Yes (assignee is the new patent owner) | Generally no (licensee holds contractual rights, not title) |
Practical guidance for practitioners
Choose an assignment when:
- The client wants to fully sell or transfer ownership (for example, as part of a company acquisition or asset sale).
- The receiving party needs clear, independent title to enforce the patent without the seller's continued involvement.
- The deal involves a lump-sum purchase of IP or an exchange for equity.
Choose a license when:
- The patent owner wants to collect royalties while retaining ownership for future products or for licensing to additional parties.
- Rights need to be scoped by territory, time, or field of use.
- The arrangement is bilateral, such as a cross-license between competitors.
Match the instrument to the intent: Whether an instrument is an assignment or a license turns on the bundle of rights actually transferred. A document labeled "license" that effectively conveys the entirety of the ownership rights in a patent may be treated as an assignment. When drafting, confirm that a license leaves the patent owner holding meaningful ownership rights rather than bare nominal title.