Ala. Code § 37-1-93

Each witness who shall appear before the commission by its order shall receive for his attendance the fees and mileage provided for witnesses in civil cases in courts of record, which shall be audited and paid by the state in the same manner as other expenses are audited and paid, upon the presentation of proper vouchers, sworn to by such witness and approved by the president of the commission; but no witness subpoenaed at the instance of parties other than commissioners shall be entitled to compensation from the state for attendance or travel, unless the commission shall certify that his testimony was material to the matter investigated, and witnesses summoned on behalf of the utility shall be paid by said utility.