ORS 34.180: Failure to answer or move for dismissal; additional pleadings.

If the defendant does not show cause by motion to dismiss or answer, a peremptory mandamus shall be allowed against the defendant. If the answer contains new matter, the same may be moved against or replied to by the plaintiff, within such time as the court or judge may prescribe. If the replication contains new matter, the same may be moved against by the defendant within such time as the court or judge may prescribe, or the defendant may countervail such matter on the trial or other proceedings by proof, either in direct denial or by way of avoidance.