(1) If any circumstance exists wherein the participation of an administrative patent judge would compromise the fairness of the proceedings in a trial, a party or an intervenor may submit challenge against the administrative patent judge.
(2) No party or intervenor shall submit challenge against an administrative patent judge after he or she has made a written or oral statement regarding the case on trial before the administrative patent judge: Provided, That the foregoing shall not apply where a party or an intervenor did not know that a ground for challenge existed, or where a ground to challenge arose subsequently.[This Article Wholly Amended on Jun. 11, 2014]