Oregon Revised Statutes Domestic Relations § 109.256

(1) The compensation of each expert witness appointed by the court or administrator shall be fixed at a reasonable amount. It shall be paid as the court or administrator shall order. The court or administrator may order that the costs of blood tests be paid by the parties in such proportions and at such times as it shall prescribe, or that the proportion of any party be paid by the county in which the proceedings are had, and that, after payment by the parties or such county or both, all or part or none of it be taxed as costs in the action.

(2) The fee of an expert witness called by a party but not appointed by the court or administrator shall be paid by the party calling the witness but shall not be taxed as costs in the action.