Under U.S. patent law, an invention lacks novelty if it was described in a printed publication anywhere prior to the date it was invented by the applicant for a patent. [35 U.S.C. 102(a)]. This usually occurs when someone who has independently invented the same invention publishes an enabling description of the invention on a date that is before the date the applicant(s) can show that the invention was completed.
It is important to note that the act (publication of a description of the invention) can be performed by anyone, and can occur anywhere. The description must have been available to the public before the applicant's date of invention. The Examiner will initially presume that the applicant's date of invention is the same as his/her/their effective U.S. filing date. If the publication occurred between his/her/their date of the invention and his/her/their filing date, it may become necessary to prove that the date of invention occurred before the publication occurred.
The courts have interpreted the phrase "printed publication" to mean any type of document that is publicly accessible. Thus, a document is a printed publication if it is printed, handwritten, recorded on microfilm, magnetic disk or tape, posted on a Web site, etcetera. Either actual, unrestricted dissemination (even on a limited basis) or mere accessibility to the public (even if there is no evidence that someone actually received the document) makes a prior art reference a printed publication. The date of receipt by addressees (as evidenced by routine business practices), as opposed to the mailing date, is the effective date of publication of magazines, journals, etcetera. Speeches and other oral presentations are not printed publications unless written copies of them are made available on an unrestricted basis.