Another area that has been left to the states is the protection of a worker's right not to join a union. These laws are commonly known as “right-to-work” laws. Missouri enacted a right-to-work law scheduled to take effect August 28, 2017, but the law was put on hold after opponents of the measure submitted petitions to put the law up for a voter referendum in November 2017.
Under the law, no employee may be required to become or remain a union member as a condition of employment (MO Rev. Code Sec. 290.590). In addition, no employee may be required as a condition or continuation of employment to:
• Pay any dues, fees, assessments, or similar charges to a union
• In lieu of the payments ...