Priority Date

The date with respect to a patent or patent application, before which pre-existing publications and disclosures are regarded as prior art for purposes of novelty and obviousness. In most jurisdictions the priority date is the filing date of the patent application. However, in U.S. law, the question of what is the priority date of an invention is complicated by the fact that the United States applied prior to the effective date of the America Invents Act the first-to-invent principle – and after the first-to-file. What is regarded as prior art is set forth in considerable detail in 35 U.S.C. §§102(a), 102(b) and 103(c). Under normal circumstances in order to qualify as “prior art” a reference must have existed as of the date of invention, which is normally presumed to be as of the filing date of the application until an earlier date is proved. There are two types of prior art, §102(a) prior art and §102(b) prior art.

  • §102(a) prior art is third party art, that is the work of parties other than the claimed inventor. For such art, all that must be shown is that it anteceded the date of invention.
  • §102(b) usually applies to disclosure by the inventor; for such art to preclude the grant of a U.S. patent, it must antecede the date of the patent application by more than one year. Further, §102(b) is also described as a “statutory bar” in that whether or not an inventor can show a date of invention earlier than one year prior to his or her application date, the inventor is not entitled to a patent if published prior art more than one year old existed as of that application date. The purpose of the statutory bar is to force inventors to the patent office.

Under §102(e) U.S. patents, if granted to an entity other than the applicant, are prior art as of their filing dates, regardless of whether they issue after the patent they are alleged to antecede. Section 103(c) refers to whether certain foreign applications filed on behalf of the same applicant can qualify as prior art for obviousness purposes.

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