It's a union buster. Proposed by Sen Crowell, who is a right wing ass from Cape Girardeau.
1. No sum shall be withheld from the earnings of any public employee for the purposes of paying any portion of dues, agency shop fees, or any other fees paid by members of a public labor organization, or individuals who are not members.
2. No public labor organization shall use or obtain any portion of dues, agency shop fees, or any other fees paid by members of the labor organization, or individuals who are not members, to make contributions or expenditures as defined in section 130.011, except upon the written authorization of the member, or individual who is not a member, received within the previous twelve months on a form 11 described by subsection 4 of this section signed by the member or nonmember and an officer of the union.
http://e-lobbyist.com/gaits/MO/SB202Crowell is the one who, several years ago, made siren sounds and fart noises into the microphone on the House floor when Democrats made points he disagreed with while debating the education budget.