ex parte reexamination

In United States patent law, a reexamination is a process whereby a third party or inventor can have a patent reexamined by a patent examiner to verify that the subject matter it claims is patentable. In order to have a patent reexamined, the party of interest must submit prior art that raises a "substantial new question of patentability".
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-- see reexamination proceeding 

If the request for ex parte reexamination is filed by a third party and not the patent owner, the third party may not participate in the ex parte proceedings beyond the filing of a reply to the patent owner's statement under 37 CFR § 1.530, if the patent owner files a statement. No other reply or submission by a third party will be considered in ex parte reexamination.

-- see MPEP 2200, 37 CFR §§ 1.501-1.570 and inter partes reexamination for more

Context: Patent