How the U.S. One-Year Patent Grace Period Works: § 102(b)

The U.S. one-year patent grace period gives an inventor twelve months after publicly disclosing an invention to file a patent application without that disclosure counting as prior art against it. The rule sits in 35 U.S.C. § 102(b)(1), and it applies only when the disclosure traces back to the inventor.¹ It is a safety net inside the first-inventor-to-file system created by the Leahy-Smith America Invents Act, not a strategy to plan around.

What Starts the Clock

The clock starts the moment an invention becomes available to the public. Section 102(a)(1) treats an invention as unpatentable if it was “patented, described in a printed publication, or in public use, on sale, or otherwise available to the public” before the effective filing date.¹ Section 102(b)(1) then carves out disclosures made within the twelve months before filing, so long as they came from the inventor.

“Printed publication” is a question of public accessibility, not format. If a person skilled in the field could find the document through reasonable effort, it qualifies: blog posts, conference papers posted online, preprint servers, and YouTube videos all fit.² A slide deck emailed to five colleagues probably does not count. The same deck uploaded to a public conference site almost certainly does.

“Public use” covers using the invention in its intended way in front of people who have no obligation to keep it secret. Demonstrating a prototype at a trade show, running visible field tests, or letting a friend try a new tool with no confidentiality agreement all qualify. The test is whether the use was accessible to the public or shielded by a secrecy obligation.

The catchall phrase “otherwise available to the public,” added by the AIA, picks up disclosures that do not fit the older categories cleanly. A live product demo streamed on social media may not be a printed publication or a traditional public use, but it still makes the invention available to the public and starts the year.

Sales and Offers to Sell

Selling or offering to sell an invention triggers the grace period the same way a publication does. The Supreme Court’s test in Pfaff v. Wells Electronics, Inc. requires two things before the critical date: the product must be the subject of a commercial offer for sale, and the invention must be ready for patenting, either through a working prototype or through drawings and descriptions detailed enough for a skilled person to build it.³ A single offer counts, even if no one accepts it.

Confidential sales are not a workaround. In Helsinn Healthcare S.A. v. Teva Pharmaceuticals USA, Inc., the Supreme Court held unanimously in 2019 that a commercial sale to a third party bound by a confidentiality agreement still places the invention on sale.⁴ The Court read the AIA’s “otherwise available to the public” language as a catchall, not as a limit on the settled meaning of “on sale.” Signing a supply agreement or accepting a purchase order under an NDA starts the twelve-month countdown.

Whose Disclosures Are Protected

The grace period shields only disclosures that originate with the inventor. Under § 102(b)(1)(A), a disclosure is not treated as prior art if it was made by the inventor, a joint inventor, or someone who obtained the information directly or indirectly from them.⁵ A graduate student’s publication is covered if the student is later named as a joint inventor on the application. A collaborator’s write-up is covered if the collaborator learned the invention from the inventor.

An independent third party who arrives at the same invention and publishes first is not covered. That disclosure did not come from the applicant, and under first-inventor-to-file, the one who files first generally wins when two people independently invent the same thing. Contemporaneous records such as lab notebooks, dated emails, and version-controlled documents matter here, because they are what proves the chain of information when it is later challenged.

Blocking Later Third-Party Disclosures

Section 102(b)(1)(B) turns the inventor’s own disclosure into a shield. Once you publicly disclose your invention, a third party’s later disclosure of the same subject matter cannot be used against your application during the remainder of the grace period.¹

The shield covers only what you actually disclosed. If you published details about components A, B, and C, and a third party later publishes on A, B, C, and D, only the overlap is neutralized. Element D remains available as prior art against your application.⁵ The format need not match: you could demonstrate at a conference while the third party publishes a journal article, and the exception still applies. Word-for-word identity is not required either. What matters is whether the subject matter in the intervening disclosure had already been made public by the inventor.

When Public Activity Is Experimental, Not Disclosure

Not every public-facing activity trips the grace period. If the primary purpose of a public use or sale is to test and perfect the invention, courts may treat it as experimental use rather than a public disclosure. Any commercial gain has to be incidental to the experimentation, not the other way around.

Courts look at several factors:

Whether the inventor kept supervision and control over the invention during testing.
Whether the invention genuinely needed real-world conditions that could not be replicated in a lab.
Whether the inventor kept systematic testing records.
Whether any customer involved was told the product was experimental.
Whether the testing period was reasonable for the type of invention or dragged on while sales accumulated.
Whether payment, if any, was structured as compensation for testing rather than as a product sale.

Market testing is not experimental use. Gauging demand, collecting purchase-intent data, or running a limited commercial launch are commercial activities. Experimental use ends once the inventor has confirmed the invention works for its intended purpose. Anything public after that point is a disclosure.

Calculating the Deadline

The twelve months run from the date of the first public disclosure to the effective filing date. Present your invention at a conference on March 15, and the application must be on file by March 15 of the following year. Miss it, and the disclosure becomes permanent prior art that destroys the novelty of the invention.⁶

If the deadline falls on a Saturday, Sunday, or federal holiday, the filing date extends to the next business day.⁷ Do not plan around that. The harder task is figuring out which event was actually the first disclosure. An informal January demo, an April preprint, and a June conference talk are three candidates, and the January demo sets the deadline if it was accessible to people without confidentiality obligations. Many inventors do not realize they have started the clock until months have gone by.

Using a Provisional Application to Lock In the Date

A provisional patent application is the standard tool for holding the priority date while the full application is prepared. It sets an effective filing date without requiring formal patent claims, and it costs much less than a non-provisional application. It still needs a written description and any necessary drawings.⁸

A non-provisional application filed within twelve months that claims the benefit of the provisional uses the earlier date as its effective filing date for grace period purposes.⁵ If no non-provisional is filed within that window, the provisional is automatically abandoned and cannot be revived.⁸

As of 2026, the provisional filing fee is $325 for a large entity, $130 for a small entity, and $65 for a micro entity.⁹ The provisional is not a license to be sloppy. Its written description has to adequately support the claims that eventually appear in the non-provisional. If the provisional describes version 1.0 and the non-provisional claims features that only appeared in version 3.0, the provisional will not establish priority for those later claims.

What the Grace Period Will Not Do for Foreign Rights

The one-year window is a feature of U.S. law. Most major patent systems apply an absolute novelty standard, meaning any public disclosure before the filing date, including one by the inventor, destroys patent eligibility. There is no cure for this in most jurisdictions.

The European Patent Convention offers only a narrow six-month exception for disclosures at certain officially recognized international exhibitions and for situations where a third party breached a confidentiality agreement. Voluntary disclosures by the inventor, such as publishing a paper or presenting at a conference, receive no protection. Japan and South Korea offer grace periods, but they function more as safety nets than strategic tools, and they typically will not protect against intervening third-party filings or disclosures that did not originate with the inventor.

The practical consequence is straightforward. If you plan to seek patent protection outside the United States, file before you disclose anything publicly. A provisional application filed before a conference presentation or journal publication preserves your priority date internationally through the Paris Convention. Publishing first and filing later works under U.S. law but leaves you with nothing in Europe and an unreliable position in most other countries.

1
Office of the Law Revision Counsel. 35 USC 102 – Conditions for Patentability; Novelty
2
United States Patent and Trademark Office. MPEP 2128 – Printed Publications as Prior Art
3
Legal Information Institute. Pfaff v. Wells Electronics, Inc.
4
Justia. Helsinn Healthcare S.A. v. Teva Pharmaceuticals USA, Inc.
5
United States Patent and Trademark Office. MPEP 2153 – Prior Art Exceptions Under 35 USC 102(b)(1) to AIA 35 USC 102(a)(1)
6
Federal Register. Changes To Implement the First Inventor To File Provisions of the Leahy-Smith America Invents Act
7
Office of the Law Revision Counsel. 35 USC 21 – Filing Date and Day for Taking Action
8
Office of the Law Revision Counsel. 35 USC 111 – Application
9
United States Patent and Trademark Office. USPTO Fee Schedule