their customs and practices shall be made by simply asking the witness or witnesses to affirm that when asked questions in the hearing, he/she will tell the truth. Section 7. Members of ICCs/IPs as Expert Witnesses. – Expert witnesses are qualified as such on account of their education or training, experience, and expertise. Education or training does not necessarily refer to formal education but also includes non-formal education or training received from elders or experts in the ICCs/IPs. A member of the ICCs/IPs possessing the appropriate non-formal education or training, experience, and expertise on matters relating to their customary laws and traditions may be considered as an expert witness. In case of conflict between the learned opinion of an anthropologist and the ICCs/IPs expert witness on customary law and traditions, the opinion of the latter shall prevail. Section 8. Quantum of Evidence. – Substantial evidence is necessary to establish a claim or defense under this Rules. RULE XII – SUBPOENA AD TESTIFICANDUM AND SUBPOENA DUCES TECUM Section 1. Power to Issue Subpoena. – The Commission en banc and the Regional Hearing Office, in the exercise of its quasi-judicial function may issue subpoena ad testificandum and subpoena duces tecum to compel the attendance of a witness or persons in a proceeding before it and to require the production and presentation of documents during a hearing. Section 2. Service of the Subpoena. – The subpoena may be personally served to the person named therein or by registered mail or by private courier. Section 3. Failure to appear. – The failure by any person without adequate cause to obey a subpoena served upon him/her shall be deemed an act in contempt of the Commission en banc or the Regional Hearing Officer who issued the subpoena. This provision shall not apply when the non-appearance is due to restraints imposed by customary law and/or tradition or for any other justifiable cause, provided the same shall be immediately communicated to the Commission or the Regional Hearing Officer prior to the date of intended appearance. RULE XIII – CONTEMPT Section 1. Direct Contempt. – The Commission en banc or the Regional Hearing Officers may summarily pass judgment on acts of direct contempt committed in the presence of, or so near the Chairman or any member of the Commission or its Regional Hearing Officers, as to obstruct or interrupt the proceeding before the same, including disrespect towards the Commissioners or the Regional Hearing Officers, offensive behavior towards other parties, refusal to be sworn in or to answer as a witness, or to subscribe to an affidavit or deposition when lawfully required to do so. Page | 20