Sheldon Richman points out how workers, as well as employers, are harmed by federal labor laws. Among other things, federal laws limit the right of workers to withhold their labor (strike) and actually limits an individual worker's ability to chose the type of representation that best suits his individual needs and preferences.
Richman speculates that the Wager Act, which forces employers to cede control of their workforce to union bosses, was a Bismarkan attempt to deflate radial labor movements, such as syndicalism, by offering unions willing to play ball with the government a role in managing the corporate state. The Wagner Act also give big businesses another set of laws that disadvantage their smaller competitors who can not as easily afford the costs associated with compulsory unionism.
The Wagner Act was one of the most egregious assaults on private property and contract in American history, and the way the system of forced unionism harms workers offers us more proof that the state is the true enemy of the working class.