Patents Q&A

What is the Patent Filing Grace Period?

Obtaining rights in an invention require affirmatively filing a patent application. There is a limited one-year grace period in the U.S. to file a patent application after the invention has been disclosed or commercialized before patent rights are lost. In the context of an inventor’s own prior activities, the term “critical date” refers to the beginning of the grace period one year before the “effective filing date” of a claimed invention. Understanding this grace period is important in order to know when patenting becomes barred, or may have already been barred, due to an inventor’s own prior actions.

The U.S. patent laws generally bar patenting if “the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention” or if “the claimed invention was described in a patent . . . or in an application for patent published or deemed published . . . [that] names another inventor and was effectively filed before the effective filing date of the claimed invention.” (35 U.S.C. § 102(a)). In other words, disclosures and commercial exploitation of an invention prior to the critical date qualify as “prior art” that can be held against a later-filed patent or patent application. Such prior art is used to evaluate the patentability (or validity) of a claimed invention.

Graphic of grace period timline
Illustration of Timeline for U.S. Patent Filing Grace Period

However, there is a one-year grace period for filing a patent application following a disclosure or commercialization of the invention by an inventor (or someone who obtained that subject matter from an inventor). This grace period is formally stated as follows:

(b) Exceptions.-

(1) Disclosures made 1 year or less before the effective filing date of the claimed invention.- A disclosure made 1 year or less before the effective filing date of a claimed invention shall not be prior art to the claimed invention under subsection (a)(1) if-

(A) the disclosure was made by the inventor or joint inventor or by another who obtained the subject matter disclosed directly or indirectly from the inventor or a joint inventor


(2) Disclosures appearing in applications and patents.-A disclosure shall not be prior art to a claimed invention under subsection (a)(2) if-

(A) the subject matter disclosed was obtained directly or indirectly from the inventor or a joint inventor;

*** or

(C) the subject matter disclosed and the claimed invention, not later than the effective filing date of the claimed invention, were owned by the same person or subject to an obligation of assignment to the same person. [see also § 102(c) regarding inventions under joint research agreements that may satisfy this provision]

35 U.S.C. § 102(b) (Post-AIA)

So if an inventor has publicly disclosed an invention or placed it on sale, the clock has begun on the one-year deadline to file a patent application. Under current U.S. law, disclosures and on-sale activities happening anywhere in the world trigger the grace period filing deadline. But disclosure of an invention more than one year earlier represents a complete bar to patentability. The grace period is not extendable.

This 1-year grace period is somewhat unique to U.S. patent law. Most other countries have what is called an absolute novelty requirement. That means a patent application must be filed before there is any disclosure of the invention. Though the specific things that do or do not count as a prior disclosure vary somewhat by country (for instance, sometimes the country in which the disclosure was made matters, and sometimes secret sales are not considered public disclosures). What this means is that even though the U.S. has a patent filing grace period, the applicant needs to consider the most restrictive patenting requirements among all relevant jurisdictions. If it is desired to pursue foreign patent protection, or even just to preserve the possibility of foreign filings, then it is important to file a patent application before any disclosure or sales activity to ensure that patent rights are preserved for all foreign countries.

Another aspect of this grace period is the exception set forth in 35 U.S.C. § 102(b)(1)(B), which says a disclosure falling within the grace period does not qualify as prior art (under § 102(a)(1)) if “the subject matter disclosed had, before such disclosure, been publicly disclosed by the inventor or a joint inventor or another who obtained the subject matter disclosed directly or indirectly from the inventor or a joint inventor.” In other words, a disclosure by someone other than the applicant (occurring one year or less before the effective filing date) can potentially be defeated and removed from the realm of “prior art” if the inventor or applicant had previously publicly disclosed the claimed invention (one year or less before the effective filing date). So, in very limited situations, a prior public disclosure within the statutory grace period can also potentially aid a patent applicant against competitors trying to patent or commercialize the invention.

In general, the initial filing of a patent application to preserve U.S. patent rights and stop the clock on the 1-year grace period encompasses both U.S. and foreign applications. The “effective filing date” (as defined in 35 U.S.C. § 100(i)) is the earlier of the filing date of a given U.S. patent application or, if there is a qualifying foreign priority or domestic benefit claim to earlier application(s), the filing date of such an earlier U.S., PCT international, or foreign application that disclosed the claimed invention. Where this can become complicated is that there may be multiple prior applications but the effective filing date is assessed on a claim-by-claim basis. The effective filing date is not necessarily the earliest prior application if the relevant “claimed invention” (as defined in 35 U.S.C. § 100(j)) was not yet disclosed in it.

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Austen Zuege is an attorney at law and registered U.S. patent attorney in Minneapolis whose practice encompasses patents, trademarks, copyrights, domain name cybersquatting, IP agreements and licensing, freedom-to-operate studies, client counseling, and IP litigation. If you have patent, trademark, or other IP issues, he can help.