Miss. Code § 13-5-67
Except in cases in which jury selection and selection of alternate jurors is governed by rules promulgated by the Mississippi Supreme Court, whenever, in the opinion of a circuit judge or chancellor presiding in a case in which a jury is to be used, the trial is likely to be a protracted one, such circuit judge or chancellor, in his discretion, may direct that one (1) or two (2) jurors in addition to the regular panel be called and impaneled to sit as alternate jurors. Alternate jurors in the order in which they are called shall replace jurors who, prior to the time the jury retires to consider its verdict, become unable or disqualified to perform their duties. Alternate jurors shall be drawn in the same manner, shall have the same qualifications, shall be subject to the same examination and challenges for cause, shall take the same oath and shall have the same functions, powers, facilities and privileges as the regular jurors. An alternate juror who does not replace a regular juror shall be discharged at the time the jury retires to consider its verdict. In capital cases the defendant and the state shall each be allowed two (2) peremptory challenges to alternate jurors in addition to those otherwise provided by law. In all other cases each party shall be allowed one (1) peremptory challenge to alternate jurors in addition to those otherwise provided by law. In any criminal case all peremptory challenges by the state shall be made before the alternate juror is presented to the defendant. The additional peremptory challenges provided for herein may be used against an alternate juror only, and other peremptory challenges allowed by law may not be used against an alternate juror.
Miss. Code § 13-5-67