law: Railways Act, 1989
  7. Power of Commissioner. 
  Subject to the control of the Central Government, the
  
  Commissioner, whenever it is necessary so to do for any of the purposes of this
  
  Act, may- 
  (a) enter upon and inspect any railway or any rolling stock used
  
  thereon;
  (b) by order in writing addressed to a railway administration,
  
  require the attendance before him of any railway servant and to require answers
  
  or returns to such inquiries as he thinks fit to make from such railway servant
  
  or from the railway administrations; and
  (c) require the production of any book, document or material
  
  object belonging to or in the possession or control of any railway
  
  administration which appears to him to be necessary to inspect.