What is prior art in United States Patent Law?

A patent is a group of exclusive rights granted to an inventor in exchange for a detailed public disclosure of an invention. The purpose of a patent is en encourage innovation and to reward inventors that share their innovative ideas with the public. To qualify for a patent, the invention must be novel, non-obvious and useful. The terms novel, non-obvious and useful may appear to have straight forward definitions. In patent law the terms have a very specific meaning that may not exactly match the dictionary definition. Whether an invention is novel or non-obvious revolves around what is known in the prior art. If an invention is described in the prior art then the invention will not be eligible for a patent because the invention could be considered obvious or not novel.

Simply stated prior art is any evidence that your invention is already known, but as stated above, the dictionary definition does not always match up with the legal definition.

The question then becomes, how is prior art defined in United States patent law? 35 U.S.C. 102 defines what is considered prior art.

It should be noted that the America Invents Act modified the definition of prior art. The American Invents Act took effect on March 16, 2013. For the purposes of this article the new definition of prior art will be discussed but if you have a patent application that was filed before March 2013, you should review the old definition of prior art.

35 U.S.C. 102(a) provides that a person shall be entitled to a patent unless—

(1) 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
(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.

The different activities and publications described in 35 U.S.C. 102(a)(1) and 35 U.S.C. 102(a)(2) are considered prior art which would prevent a patent application from being granted but 35 U.S.C. 102(b) creates some exceptions which would still allow a patent application to be granted.

35 U.S.C. 102(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; or
(B) 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.
(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;
(B) the subject matter disclosed had, before such subject matter was effectively filed under subsection (a)(2), 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; 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.

Reading the law directly is sometimes difficult so lets gives some examples to help explain the law.

If an inventor sells his invention to the public, that would be considered prior art under 102(a)(1). The inventor could still get a patent on the invention if a patent application is filed within one year of the sale of the invention.

If another person described the invention in a scientific journal that would be considered prior art under 102(a)(1). The inventor could still get a patent if the third party learned about the invention from the inventor and the inventor files a patent application within one year of the scientific journal’s publication. If the inventor did not tell the third party about the invention than the exception does not apply.

If another person files a patent application which was published in the United States that would be considered prior art under 102(a)(2). But if the inventor filed his patent application first, it would not be considered prior art under 102(a)(2) or it would not be considered prior art if the inventor told the other person about the invention under 102(b)(2)(A).

Determining what is considered prior art can be tricky. It is best to consult with an experienced patent attorney to help analyze what may be considered prior art before you file a patent application.

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