ORS § 136.570
If either party in a criminal action desires more than 10 witnesses, as provided in ORS 136.565 and 136.567, application therefor shall be made to the court or judge thereof by motion for an order allowing the issuance of subpoenas for such additional witnesses, which motion shall be supported either by the statement of the district attorney or city attorney in writing or by the affidavit of the defendant. The statement or affidavit shall state the names of such witnesses, their places of residence and the facts expected to be proved by each of them. The court or judge thereof shall make an order allowing the issuance of subpoenas for so many of such witnesses as appear from such statement or affidavit to be necessary and material to a fair, full and impartial trial.
ORS 136.570