Refers to a patent office proceeding to re-examine or review the grant of a patent, usually in light of prior art not before the patent office in the original examination, where third parties, for example competitors, are allowed to be present and argue against the re-grant of the patent or for more limited claims. Inter Partes Reexamination was restyled Inter Partes Review under the America Invents Act : See Ex Parte Reexamination.