Oregon Revised Statutes Procedure in Criminal Matters Generally § 135.173

The Oregon Evidence Code shall apply in any preliminary hearing under this chapter, except that hearsay may be admitted if the court determines that it would impose an unreasonable hardship on one of the parties or on a witness to require that the primary source of the evidence be produced at the hearing, and if the witness furnishes information bearing on the informant's reliability and, as far as possible, the means by which the information was obtained.