Patents Q&A

What Is Prior Art?

The phrase “prior art” is used extensively in relation to patents and patenting. But what is prior art? What does this term refer to? The following article will explain how this term is used in patent law.

Basic Overview

Prior art refers to what was already known that is relevant to patentability. More particularly, it is qualifying existing knowledge that is relevant to questions of novelty and nonobviousness (or inventive step), which are two requirements for patentability, for an invention recited in a given claim of a patent or patent application.

Of course, there are some further nuances here about what exactly is considered relevant to patentability and what is not, and what legally qualifies as prior art under applicable law. Many of those nuances are explained further below.

Prior Art is Old Knowledge

First of all, prior art has to be old enough. It always has to be something that was already known or came before before a particular date associated with a given patent or patent application. So the “prior” part of the term “prior art” means something was known sufficiently earlier or before what given inventor(s) are claiming is their patentable invention. This is about dividing technical knowledge into older stuff that might call the patentability of an invention into question and later stuff that might infringe claim(s) of a patent to that invention.

For any given patent or patent application, there is a critical date that establishes what is old enough to be prior art. Something before the critical date is prior art and anything after is not. The point in time that constitutes a critical date will be established by the patent laws of a particular jurisdiction. It can vary based on whether a jurisdiction follows a first-to-file patent system or a first-to-invent patent system, for example. It can also vary on a claim-by-claim basis—there may be different priority dates for different claims, which means some things may be prior art against certain claims but not others.

Prior Art is Knowledge of Useful Arts

The “art” part of the term “prior art” refers to knowledge about the useful arts. The “useful arts” is basically an old-fashioned term that refers to technical knowledge pertaining to what today is more commonly called science and engineering. Just as there are different fields of science and engineering, there are different types of arts. So this term is not limited to any particular area or kind of technical knowledge. But it does not refer to paintings, sculptures, or similar artworks that might appear in a museum.

The term “prior art” can refer to the collective body of relevant prior technical knowledge. That means it is proper to say that something falls within the prior art, as in being a part of that body of pre-existing knowledge. It is common to refer to a “prior art reference”, “prior art product”, or the like in reference to a particular instance of something that qualifies (or allegedly qualifies) as prior art.

Prior Art is Essentially Public Knowledge

In general, prior art refers to information that was sufficiently accessible to the public. This might have been in the form of commercially-available products or services, or in the form of articles, books, videos, etc. Importantly, something that was “secret” and not available to the public usually will not qualify as prior art. For instance, an unpublished draft of a book or article will not qualify as prior art. But there are some exceptions that may allow certain secret or confidential activities to qualify as prior art, mainly relating to confidential on-sale activities.

A crucial exception (at least in the USA) is that any sale or offer for sale can potentially qualify as prior art. The U.S. on-sale bar still applies to prior confidential, private, or otherwise secret commercial sales or offers for sale. In other words, a confidentially or non-disclosure (NDA) agreement will not remove something that was on sale from the realm of prior art. Such confidential sales still involve a third-party (who is part of the public) gaining access to an invention. Also, inventor(s)’ own prior activities can potentially be used as prior art against the inventor(s)’ later patent application or patent, unless the inventor(s)’ application was filed in the statutory grace period.

Laws Vary By Jurisdiction

Prior art is also something defined by the patent laws of a given jurisdiction. This means that definitions of what is and is not considered prior art can and do vary between different countries. There is no universal harmonization of patent laws in this respect. So it is possible something might qualify as prior art in one country but not in another.

In the USA, what constitutes prior art is set out in § 102 of the patent laws (35 U.S.C. § 102). This portion of the current patents laws is written in a very confusing manner. But it establishes that prior art can include a patent, a published patent application, a printed publication (which can also include patents and published patent applications), products or processes that were in public use or on sale, as well as things that were otherwise available to the public before the effective filing date of the claimed invention. U.S. patent law also contain some exceptions that can disqualify certain references from being used as prior art.

In other countries, however, the patent laws may differ significantly. For instance, some countries have no on-sale bar, only a public use bar to patenting. This means that secret or confidential sales may not qualify as prior art, even if those prior secret sales involved the identical invention. And few other countries have a filing grace period like the U.S. Some jurisdictions may also have limits on the use of prior art, such as making an applicant’s prior patent applications available as prior art only for novelty determinations but not inventive step/obviousness determinations. It is important to consider laws of each relevant jurisdiction separately, because differences in laws can mean that what qualifies as prior art differs between jurisdictions.

Laws Change Over Time

What qualifies as prior art can also change over time in a given jurisdiction as laws are modified or interpreted by courts.

U.S. patent laws have changed over time, including modifications to the definitions of what does and does not qualify as prior art. Significantly, the America Invents Act (AIA) had provisions that went into effect March 16, 2013 that eliminated certain first-to-invent provisions and altered other aspects of what qualifies as prior art. For example, the AIA eliminated certain geographic restrictions on what qualifies as prior art—no longer requiring that certain things happen in this country (i.e., in the USA) to be prior art. Patents and patent applications with pre-AIA effective filing dates are therefore subject to different definitions of what qualifies as prior art than post-AIA ones. Laws in other countries have also changed over time.

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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.