225 ILCS 705/6.12
It shall be unlawful for the operator of any mine to have in his service as mine examiner any person who does not hold a certificate of competency issued by the Mining Board except that anyone holding a mine manager's certificate may serve as a mine examiner. The mine manager shall not act in the capacity of mine examiner while acting as mine manager. However, whenever any exigency arises by which it is impossible for any operator to secure the immediate services of a certificated examiner, he may employ any trustworthy and experienced man of the mine inspection district to act as temporary mine examiner for a period not exceeding 7 days, and with the approval of the State Mine Inspector of the district, for a further period not exceeding 23 days. The employment of persons who do not hold certificates as mine examiners shall in no case exceed the limit of time specified herein, and the State Mine Inspector shall not approve of the employment of such persons beyond the 23 day limit.
225 ILCS 705/6.12