Patent ownership basics
Section 261 of the Patent Act sets three simple rules: a patent is personal property, an assignment has to be in writing, and recording it on time protects the new owner. Here is what each rule means and why it matters when you check who owns a patent.
35 U.S.C. 261 does three things. First, it says patents have the attributes of personal property, so a patent can be bought, sold, and used as collateral like other property. Second, it says patents and any interest in them can be assigned only by an instrument in writing. A spoken promise or a handshake does not transfer a patent. Third, it sets the rule for recording an assignment with the United States Patent and Trademark Office.
The recording rule is the part that decides ownership disputes. In the words of the statute, an assignment is “void as against any subsequent purchaser or mortgagee for a valuable consideration, without notice, unless it is recorded in the Patent and Trademark Office within three months from its date or prior to the date of such subsequent purchase or mortgage.”
An assignment is fully valid between the buyer and seller the moment it is signed. It does not have to be recorded to be real. Recording matters for a different reason: it protects the new owner against a later buyer.
Say a company assigns a patent to Buyer A but the assignment is never recorded. Months later the same company assigns the same patent to Buyer B, who pays value and has no notice of the earlier deal. Under Section 261, Buyer A can lose to Buyer B unless Buyer A recorded within three months of signing, or before Buyer B’s purchase. Recording promptly is how the first buyer keeps priority.
For anyone reviewing a patent before a transaction, this is why recording dates are worth checking. An assignment that was signed years ago but recorded late, or never recorded, is a sign that ownership may not be as clean as the current record suggests.
Recorded assignments live in the USPTO Patent Assignment Database. Each recorded document is given a reel and frame number, for example 068526/0728. That number is the standard way to cite a specific record so anyone can pull the same document and read it.
To review a single patent, three things are worth reading together:
Doing this for one patent is quick. Doing it for a portfolio of dozens, and reconciling names that are spelled differently across records, is where the time goes.
Patencial reads the recorded assignments for each patent, lines up the execution dates against the recording dates, and flags any assignment recorded outside the three-month window or not recorded at all. It also checks that each transfer connects to the next, so a missing or late recording does not go unnoticed.
Every finding is cited to the USPTO reel and frame, so an attorney can pull the same record and decide whether the issue matters for the deal. Patencial reports what the record shows. Whether a flagged item is material is a legal judgment.
It is the section of the Patent Act that treats patents as personal property, requires patent assignments to be in writing, and sets the rule for recording assignments with the USPTO. It is the legal basis for how patent ownership is transferred and proven.
No. An assignment is valid between the two parties once it is signed in writing. Recording is about protecting the new owner against later buyers. If the assignment is not recorded in time, a later buyer who pays value without notice of the earlier transfer can take priority.
Under Section 261, an unrecorded assignment can be void against a later purchaser who pays value without notice, unless the earlier assignment was recorded with the USPTO within three months of its date, or before that later purchase. Recording promptly is how a buyer keeps priority.
An assignment transfers ownership of the patent. A license grants permission to use the patent while ownership stays with the licensor. Section 261 covers assignments and other transfers of an interest in the patent.
They are recorded in the USPTO Patent Assignment Database. Each recorded document gets a reel and frame number, which is the citation used to point to a specific record.
Patencial reads the recorded assignments for each patent, checks the execution and recording dates against the three-month window, and flags assignments that were recorded late or never recorded. Every finding cites the USPTO reel and frame.
Patent chain of title verification
Reconstruct ownership from the named inventors to the current assignee, with every defect cited to a USPTO record.
Read guidePost-AIA chain of title gaps
How assignee filing under the America Invents Act can leave an inventor assignment unrecorded, and how to find the gap.
Read guidePatent security interests and liens
How a pledged patent shows up in the USPTO record, and why an unreleased lien blocks a clean transfer.
Read guidePatent due diligence for M&A
What patent diligence checks before a deal closes, starting with clean ownership of every patent.
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