law: Passports Act, 1967
  7. Duration of travel document
  A passport or travel document shall, unless
  
  revoked earlier, continue in  force for such period as may be prescribed
  
  and different periods may be prescribed for different classes of passports or
  
  travel documents or for different categories of passports or travel documents
  
  under each such class:
  Provided that a passport or travel document may
  
  be issued for a shorter period than the prescribed period-
  (a) if the person by whom it is required so
  
  desires; or
  (b) if the passport authority, for reasons to
  
  be communicated in writing to the applicant, considers in any case that the
  
  passport or travel document should be issued for a shorter period.