Oregon Revised Statutes Procedure in Criminal Matters Generally § 136.250

All peremptory challenges may be taken by the state or defendant, but when several defendants are tried together, the defendants are entitled to the number of challenges they would have had if each defendant had been tried separately. When two or more defendants are tried together, the state is entitled to the same total number of peremptory challenges as the sum of the peremptory challenges the defendants could have exercised.