Except where specifically authorized by the Utah Constitution, or statutes, no agency shall hire legal counsel, and the attorney general alone shall have the sole right to hire legal counsel for each such agency. Where the Legislature has provided by statute for separate agency counsel, no such counsel may act as an assistant attorney general nor as a special assistant attorney general unless the attorney general shall so authorize. Unless he hires such legal counsel from outside his office, the attorney general shall remain the sole legal counsel for that agency. If outside counsel is hired for an agency, then the costs of any services to be rendered by this counsel shall be approved by the attorney general before these costs are incurred. The attorney general shall approve all billing statements from outside counsel and shall pay the full costs of this counsel unless the agency by legislative appropriation or in the form of costs, fees, fines, penalties, forfeitures or proceeds reserved or designated for the payment of legal fees receives from any other source the equivalent cost or a portion thereof, in which case the attorney general may bill the agency for the services; provided, the agency may deduct any unreimbursed costs and expenses incurred by the agency in connection with the legal service rendered.