In order for an invention to be patentable, it must be new. But the term "new" has a particular meaning under U.S. patent law as it was revised in 2011. A person shall be entitled to a patent unless (1) the subject matter was publicly disclosed (verbal or written publications, public uses, sales, and the like) anywhere in the world before the effective filing date of the claimed invention, (2) the subject matter was described in a U.S. Patent, U.S. Patent Application, or PCT Patent Application designating the U.S. before the effective filing date of the claimed invention.
Several exceptions to the law above exist. For example, a one-year grace period is provided for inventors who make the public disclosures noted above. In addition, subject matter that was directly or indirectly described by an inventor or joint inventor in a U.S. Patent, U.S. Patent Application, or PCT Patent Application will not be considered to be prior art against the patent application. This is effective for patent applications that are commonly owned by two or more entities, as well as joint applicants under a Joint Research Agreement.
It does not matter when the invention was made, or whether the printed publication or public use was by the inventor himself/herself or by someone else. If the inventor describes the invention in a printed publication or uses the invention publicly, or places it on sale, he/she must apply for a patent before one year has gone by. Otherwise any right to a patent will be lost. In addition, the inventor must file on the date of public use or disclosure in order to preserve patent rights in many foreign countries.