Idaho Code § 61-603
The commission and each commissioner shall have power to administer oaths, certify to all official acts, and to issue subpoenas for the attendance of witnesses and the production of papers, waybills, books, accounts, documents and testimony in any inquiry, investigation, hearing or proceeding in any part of the state.
Each witness who shall appear, by order of the commission or a commissioner, shall receive for his attendance the same fees allowed by law to a witness in civil cases, in the district court, and mileage at ten cents (10¢) for every mile of travel one (1) way by the nearest generally traveled route in going to the place where the attendance of a witness is required, which amount shall be paid by the party at whose request such witness was subpoenaed.
When any witness who has not been required to attend at the request of any party shall be subpoenaed by the commission, his fees and mileage shall be paid from the funds appropriated for the use of the commission in the same manner as other expenses of the commission are paid: provided, that the commission may at its discretion refuse to allow the mileage and attendance of any witness subpoenaed before it that is in the employ of any public utility defined in this act.
Any witness subpoenaed except one whose fees and mileage may be paid from the funds of the commission, may at the time of service, demand the fee to which he is entitled for travel to and from the place at which he is required to appear and one (1) day's attendance. If such witness demands such fees at the time of service, and they are not at that time paid or tendered, he shall not be required to attend before the commission or commissioner, as directed in the subpoena, unless the commission shall by order indorsed on the subpoena require any such witness to attend, irrespective of the fact that such mileage and attendance are not paid on demand. All fees or mileage to which any witness is entitled under the provisions of this section may be collected by action therefor instituted by the person to whom such fees are payable. No witness furnished with free transportation shall receive mileage for the distance he may travel on such free transportation.
Idaho Code § 61-603