Except as otherwise provided by law, witness' fees for each day's actual attendance, when legally required to attend, or if the witness attends voluntarily and is called to testify, before a coroner's jury, are twelve dollars ($12) a day and mileage for each mile actually traveled in attendance as a witness, one way only, twenty cents ($0.20). That per diem and mileage shall be a county charge.
Ca. Gov. Code § 68095