Missouri Revised Statutes Title IX. Suffrage and Elections § 115.445. No one but voter in booth, exception

1. Except as provided in subsections 2 and 3 of this section, no one other than the voter shall be permitted in any voting booth or permitted to be in any position where he may see how a voter is voting.

2. If any voter, after entering a voting booth, asks for further instructions concerning the manner of voting, two election judges of different political parties shall give such instructions. Such judges shall not enter the voting booth unless it is impossible to give the instructions otherwise. After giving the instructions, the judges shall leave the area and take all necessary measures to insure that the voter casts his vote in secret.

3. If any voter declares under oath to the election judges that he cannot read or write, is blind or has any other physical disability and cannot vote his ballot, he may be assisted by the election judges or by any person of his own choice other than a judge. If the voter asks for the assistance of election judges, two judges of different political parties shall go to the voting booth and cast his vote as he directs. If the voter asks for the assistance of someone other than election judges, the assistant shall go to the voting booth with the voter and cast his vote as he directs. No person, other than election judges and members of such voters' immediate families, shall assist more than one voter at one election.

4. A child under the age of eighteen shall be allowed to accompany his or her parent, grandparent, or guardian into a voting booth.