law: The Administrative Tribunals Act, 1985
  7. Vice-Chairman to Act as Chairman or to Discharge his Functions in Certain Circumstances. -
  (1) In the event of the occurrence of any
  
  vacancy in the office of the Chairman by reason of his death, resignation or
  
  otherwise, the Vice-Chairmen or, as the case may be, such one of the
  
  Vice-Chairmen as the appropriate Government may, by notification, authorize in
  
  this behalf, shall act as the Chairman until the date on which a new Chairman,
  
  appointed in accordance with the provisions of this Act to fill such vacancy
  
  enters upon his office. 
  (2) When the Chairman is unable to discharge
  
  his functions owing to absence, illness or any other cause, the Vice-Chairman
  
  or, as the case may be, such one of the Vice-Chairmen as the appropriate
  
  Government may, by notification, authorize in this behalf, shall discharge the
  
  functions of the Chairman until the date on which the Chairman resumes his
  
  duties.