12. The Commission shall, while investigating any matter referred to in clause (a) or inquiring into any complaint referred to in clause (b) of sub-section (1) of Section 11, have all the powers of a civil court trying a suit and in particular in respect of the following matters, namely:
(a) summoning and enforcing attendance of any person and examining him on oath;
(b) requiring the discovery and production of any document;
(c) receiving evidence on affidavits;
(d) requisitioning any public record or copy thereof from any court or office;
(e) issuing commission for the examination of witness and documents; and
(f) any other matter that may be prescribed.
Provided that no person who is holding the office of the Chief Secretary, Principal Secretary of Secretary to the state Government or is Head of the Department employed in connection with the affairs of the State Government shall be summoned or required to attend in person under clause (a) unless prior approval of the State Government has been obtained and such person shall be deemed to have complied with the summons if he causes a person not below the rank of Deputy Secretary or, as the case may be, a person holding a post equivalent thereto to attend the Commission in compliance with the summons instead of attending in person;
Provided further that the summons issued under clause (a) shall clearly indicate the purpose for which the person concerned has been summoned and when any person is summoned to produce a document without being summoned to give evidence, he shall be deemed to have complied with the summons if he causes such document to be produced instead of attending personally to produce the same.