Section 10(1)(a) in The Tribunal, Appellate Tribunal and other Authorities (Qualifications, Experience and other Conditions of Service of Members) Rules, 2017
(a)the Chairman, Chairperson, President, or Presiding Officer of the Security Appellate Tribunal, the Central Government shall have the power to appoint the senior most Vice-Chairperson or Vice-Chairman, Vice-President or in his absence, one of the Accountant Member, Administrative Member, Judicial Member, Expert Member, Law Member, Revenue Member, Technical Member, or Member of the Tribunal, Appellate Tribunal or, as the case may be, Authority to officiate as Chairperson, Chairman, President or Presiding Officer.