Missouri Revised Statutes Title XXXIV. Juries § 494.432. Postponement of jury duty, when

1. Individuals scheduled to appear for jury service have the right to postpone the date of their initial appearance for jury service one time only for reasons other than undue influence or extreme physical or financial hardship. When requested, postponements shall be granted, provided that:

2. A subsequent request to postpone jury service may be approved by a judicial officer only in the event of an extreme emergency, such as a death in the family, sudden grave illness, or a natural disaster or national emergency in which the prospective juror is personally involved, that could not have been anticipated at the time the initial postponement was granted. Prior to the grant of a second postponement, the prospective juror must fix a date certain on which the individual will appear for jury service within six months of the postponement on a date when the court will be in session.