Orders constituting Appellate Tribunal to be final and not to invalidate its proceedings

No order of the Central Government appointing any person as the 1[Chairperson or the Member] of a [Appellate Tribunal] shall be called in question in any manner and no act or proceeding before a [Appellate Tribunal] shall be called in question in any manner on the ground merely of any defect in the constitution of a 2[Appellate Tribunal].