law: National Environment Tribunal Act, 1995
  11. Vice-Chairperson to act as Chairperson or
  
  to discharge his functions in certain circumstances
  (1) In the  event of the occurrence
  
  of any vacancy in the office of the Chairperson by reason of his death,
  
  resignation or otherwise, the Vice-Chairperson or, as the case may be, such one
  
  of the Vice-Chairpersons, as the Central Government may, by notification,
  
  authorize in this behalf, shall act as the   Chairperson 
  
  until the date on which a new Chairperson, appointed in accordance with the
  
  provisions of this Act to fill such vacancy, enters upon his office.
  (2) When the Chairperson in unable to
  
  discharge his functions owing to absence, illness of any other cause, the
  
  Vice-Chairperson or, as the case may be such one of the Vice-Chairpersons, as
  
  the Central Government may, by notification, authorize in this behalf, shall
  
  discharge the functions of the Chairperson until the date on which the
  
  Chairperson resumes his duties.