Whenever the attorney general is sick or absent, or unable to attend, or is interested in any cause or proceeding, civil or criminal, which it is or may be his duty to prosecute or defend, the court in which said cause or proceeding is pending may appoint some competent attorney to prosecute or defend such cause or proceeding, and the attorney so appointed shall have the same power and authority in relation to such cause or proceeding as the attorney general would have had if present and attending to the same.