law: 42. Power of Commissioner and other authorities to take evidence on oath, etc.
  (1) The Commissioner or any person appointed under sub-section (2) of section 9 to assist him shall, for the purposes of this Act, have the same powers as are vested in a court under the Code of Civil Procedure, 1908 (5 of 1908), when trying a suit, in respect of the following matters, namely:
  (a) enforcing the attendance of any person and examining him on oath or affirmation;
  (b) compelling the production of accounts and documents; and (c) issuing commissions for the examination of witnesses, and any proceeding under this Act before the Commissioner or any person appointed under sub-section (2) of section 9 to assist him shall be deemed to be a judicial proceeding within the meaning of sections 193 and 228 and for the purposes of section 196 of the Indian Penal Code (45 of 1860).
  (2) Subject to any rule made in this behalf, any authority referred to in sub-section (1) may impound and retain in its custody for such period as it thinks fit, any books of accounts or other documents produced before it in any proceedings under this Act:
  Provided that a person appointed under sub-section (2) of section 9 to assist the Commissioner shall not
  (a) impound any books of accounts or other documents without recording his reasons for so doing; or
  (b) retain in his custody any such books or documents for a period exceeding thirty days, without obtaining the approval of the Commissioner therefor.