law: Railways Act, 1989
  117. Statement made before Commissioner. 
  No statement made by a person in the course of giving evidence
  
  in an inquiry before the Commissioner shall subject him to, or be used against
  
  him in, any civil or criminal proceeding, except a prosecution for giving false
  
  evidence by such statement:
  Provided  that the statement is- 
  (a) made in reply to a question which is required by the
  
  Commissioner to answer; or
  (b) relevant to the subject-matter of the inquiry.