States have little regulatory control over private labor unions. This is because protections are given to most labor organizations in the National Labor Relations Act (NLRA), the federal law governing labor unions. The NLRA “preempts” all state laws that attempt to regulate unions; that is, it overrides state law in the areas that it covers, which includes almost all types of private employment. However, in the areas it does not cover, such as the rights of public employees, farm workers, and employees of businesses that do not engage in interstate commerce, the states are free to make their own provisions.
The South Dakota Labor Employment Relations Act is similar to the federal labor law. It covers all employers except the U.S. government and the state government (SD Cod. Laws Sec. 60-9A-1et seq.). The law applies to all employees except domestic servants, farm and ranch laborers, and supervisory employees and gives covered employees the right to organize, bargain collectively, and strike (SD Cod. Laws Sec. 60-9A-2).