5 GCA § 9218: Depositions.

On the verified petition of any party, an agency may order that the testimony of any material witness residing within or without the territory of Guam be taken by deposition in the manner prescribed by law for depositions in civil actions. The petition shall set forth the nature of the pending proceedings; the name and address of the witness whose testimony is desired, a showing of the materiality of his testimony, a showing that the witness will be unable or cannot be compelled to attend; and shall request an order requiring the witness to appear and testify before an officer named in the petition for that purpose. Where the witness resides outside the territory of Guam and where the agency has ordered the taking of his testimony by deposition, the agency shall obtain an order of court to that effect by filing a petition therefor in the Superior Court.