Mo. Rev. Stat. § 115.085
No person shall be appointed to serve as an election judge who is not a registered voter in this state. Each election judge shall be a person of good repute and character who can speak, read, and write the English language. No person shall serve as an election judge at any polling place in which his or her name or the name of a relative within the second degree, by consanguinity or affinity, appears on the ballot. However, no relative of any unopposed candidate shall be disqualified from serving as an election judge in any election jurisdiction of the state. No election judge shall, during his or her term of office, hold any other elective public office, other than as a member of a political party committee or township office, except any person who is elected to a board or commission of a political subdivision or special district may serve as an election judge except at a polling place where such political subdivision or special district has an issue or candidate on the ballot. In any county having a population of less than two hundred fifty thousand inhabitants, any candidate for the county committee of a political party who is not a candidate for any other office and who is unopposed for election as a member of the committee shall not be disqualified from serving as an election judge.
§ 115.085, RSMo