Okla. Stat. tit. 38, § 38-21: Drawing of names - Additional drawings - Period of service

If a grand jury is ordered, the number stated in the judge's

order, not to exceed one hundred, shall be summoned as grand jurors,

and the grand jury shall be impaneled from said persons. The judge

of the district court shall order the court clerk, one of his or her

deputies or the court administrator to order the stated number of

jurors from the Administrative Director of the Courts. In any

district court where an electronic jury management system is

implemented pursuant to Section 13 of this act, the judge may order

the stated number of jurors to be randomly selected and summoned by

the court clerk or trial court administrator utilizing the jury

management system, and the district court may use the jury

management system to randomly select the names of the grand or petit

jurors and alternate jurors from the panels so drawn. In addition

to the twelve (12) grand jurors to be impaneled, three additional

persons shall be selected as alternate grand jurors. The alternate

grand jurors shall attend all functions of the grand jury during its

term and shall be subject to all laws governing grand jurors.

Provided that, no alternate juror shall participate in any

deliberations of the grand jury until appointed to fill a vacancy.

If the judge so directs, the persons summoned for the grand jury

panel who are not used thereon may be transferred to the petit jury

panel. Additional and other drawing of as many names as the court

may order may be had at any such time as the court or judge may

order for the completion of a grand or petit jury panel, or for the

impaneling of a new grand or petit jury if, in the judgment of the

court, the same shall be necessary, or if, for any cause, the court,

in its discretion, shall deem other jurors necessary. The court may

excuse or discharge any person drawn and summoned as a grand or

petit juror whenever, in its discretion, such action shall be deemed

expedient. No person may be required to render service as a petit

juror for more than one (1) day in any one calendar year unless he

or she is selected to serve in a trial or is under consideration to

serve in a trial and such consideration covers a period of two (2)

or more days. Once selected, a juror shall serve on the jury for

the duration of the trial unless excused by the presiding judge.