Penal Code section 1334.3
(a)
If a person in any state, which by its laws has made provision for commanding persons within its borders to attend and testify in criminal prosecutions or grand jury investigations in this state, is a material witness in a prosecution pending in a court of record in this state, or in a grand jury investigation, a judge of such court may issue a certificate under the seal of the court stating these facts and specifying the number of days the witness will be required. This certificate shall be presented to a judge of a court of record in the county of such other state in which the witness is found.(b)
If the witness subpoenaed to attend and testify in this state is at the time he or she is required to appear and testify an inmate of a state prison, county jail, or other penal facility, the witness shall, while attending in this state as a witness, be furnished food and lodging in the jail or other appropriate penal facility in the county in which the witness is attending court, and food and lodging of that penal facility shall be rendered in lieu of the per diem specified in subdivision (a).
Source:
Section 1334.3, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=PEN§ionNum=1334.3.
(accessed Apr. 24, 2025).