Oregon Revised Statutes Procedure in Criminal Matters Generally § 136.260

(1)(a) In the trial of a person charged with a crime, the court may in its discretion, after the jury is impaneled and sworn, direct the calling of additional jurors, to be known as “alternate jurors.” The court may call:

(b) Jurors called under paragraph (a) of this subsection:

(c) In the drawing of alternate jurors, the names of jurors excused for cause or on peremptory challenges in the selection of the jury to which the jurors shall serve as alternates must be excluded from the names from which the drawing is made.

(a) If one or two alternate jurors are to be impaneled, each side is entitled to one peremptory challenge.

(b) If three or four alternate jurors are to be impaneled, each side is entitled to two peremptory challenges.

(c) If five or six alternate jurors are to be impaneled, each side is entitled to three peremptory challenges.