IRF

In United States patent practice, "reexamination" refers to the process of requesting that the patent office once again subject an issued patent to further examination, usually accompanied by newly discovered prior art and/or an explanation of the relevance of the prior art to the claimed invention. Unlike reissue, reexamination may be requested by anyone, not only the patent holder or inventor, although whoever requests reexamination must also submit the fee (which is about equal to the full cost of filing a new patent application). When a reexamination is completed, a Reexamination Certificate is published with the same publication number (but a different kind code). This is not a complete patent, but is only a front page with statements about the status of each of the claims (rejected, affirmed, amended).

International patent applications (PCT) and regional patent applications cover a number of countries (designated states) in a single application. At 30 months from the filing date of the international application or from the earliest priority date of the application if a priority is claimed, the international phase ends and the international application enters in national phase (covering a single country i.e. US, FR, CN) and/or regional phase as a regional patent application. See Patent Offices for access to lists of patent offices.

Inventor or assignee may request reissue of a patent to correct defects in the patent description or drawing or to correct claims. The resulting publication is a Reissue patent whose publication number is in the format of REnnnnnn.

Fees paid nationally to keep a patent, once granted, in force during its allowed maximum life (generally 20 years from filing date).