What are the On-Sale Bar and the Grace Period?
The one-year clock in 35 U.S.C. § 102(b), what starts it (including confidential sales), what the grace period does and does not forgive, and the absolute-novelty trap abroad.
Definition
The on-sale bar is the rule under 35 U.S.C. § 102 that an invention sold or offered for sale before the effective filing date is prior art against the applicant's own patent. The grace period is the one-year exception in § 102(b)(1) that excludes an inventor's own disclosures, sales, and public uses made within the year before filing. Together they set the deadline by which a US application must be filed after the invention is commercialized or disclosed.
Key Facts
- The clock: One year from the inventor's first public disclosure, public use, sale, or offer for sale to the effective filing date; a provisional stops it
- Confidential sales count: Helsinn v. Teva (2019) held that a commercial sale places the invention "on sale" even if the buyer is bound to keep the invention confidential
- Offers count: A commercial offer for sale is enough; the sale need not close
- Ready for patenting: The invention must have been reduced to practice or described in enabling drawings at the time of the sale, under Pfaff v. Wells (1998)
- Experimental use: Testing to determine whether the invention works is not a public use or sale, but market testing is
- No grace period abroad: Europe, China, and most other jurisdictions require absolute novelty; any public disclosure before the priority date destroys rights, with narrow exceptions
What Triggers the Bar
- Selling or offering to sell a product that embodies the claims, including to a distributor or a single customer
- A supply agreement or purchase order for the invention, even before it is manufactured
- Public demonstration at a trade show, conference, or investor event
- Publication in a paper, thesis, website, or marketing material
- Public use of a process, or sale of a product made by a secret process, which bars the process claims
Confidential disclosures under NDA to a partner, and offers to sell services for developing the invention rather than the invention itself, generally do not trigger it.
What the Grace Period Forgives
Within the year before filing, § 102(b)(1) excludes disclosures made by the inventor, by someone who obtained the subject matter from the inventor, and disclosures by third parties that came after the inventor's own public disclosure. It does not protect against an independent third-party disclosure that came first, and it offers no protection outside the US.
The Practical Rules
- File before the launch, the paper, the pitch, and the pilot: A provisional costs little and starts the priority chain
- Track first-disclosure dates in the invention disclosure: The one-year clock is calculated from them
- Treat international rights as lost on disclosure: If foreign protection matters, the grace period is irrelevant
- Review sales contracts for the on-sale bar: A signed supply agreement before filing has cost companies their patents
Docketing the one-year bar date from the first known disclosure is standard practice, and structured invention disclosure management that captures planned and past disclosures is how the date becomes known in time to act.
Frequently Asked Questions
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How long do you have to file a patent after selling a product?
In the US, one year from the first sale, offer for sale, or public disclosure. After that the invention is barred. Outside the US, most countries have no grace period, so foreign rights are usually lost at the moment of the first public disclosure or sale unless a priority application was already on file.
Does a confidential sale trigger the on-sale bar?
Yes. In Helsinn v. Teva (2019) the Supreme Court held that a sale to a third party who is obligated to keep the invention confidential still places the invention "on sale" under the America Invents Act, so the one-year clock starts.
Does an offer for sale count even if no sale happens?
Yes. A commercial offer for sale that could be accepted to form a binding contract triggers the bar, provided the invention was ready for patenting at the time. Preliminary negotiations that do not amount to an offer generally do not.
What is the experimental use exception?
Use or testing of the invention to determine whether it works for its intended purpose, under the inventor's control, is not a public use or sale. Testing to gauge customer demand, or use after the invention is known to work, is not experimental and starts the clock.
Does the US grace period protect foreign patent rights?
No. The one-year grace period is a feature of US law. The European Patent Office, China, and most other jurisdictions apply absolute novelty, with only narrow exceptions such as disclosure at certain recognized exhibitions or by evident abuse. A public disclosure before the priority date generally destroys foreign rights.
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