This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
It seems to have been held originally that a combination between workmen, for the purpose of raising their wages, was necessarily illegal, no matter what means might be employed.1 It was also held that a combination between employers for the purpose of keeping down wages was illegal.2 The rate of wages was probably selected by the court stating this view of the law, because, at the outset, the rate of wages was the chief thing in which the combination of employers and employes was concerned. The view that combinations of employes for the purpose of raising their wages, securing a better condition in hours of labor, circumstances of labor, and the like, is necessarily illegal, has long since been abandoned.3 At modern law the fact that employes or others act in combination is not necessarily illegal; and as long as it does not attempt to accomplish an illegal purpose, or to use illegal means, its acts are not regarded as illegal.
A labor union can not lawfully exercise coercion to compel its members to vote for certain designated public officers,4 whether they have pledged themselves in advance to support the candidates of the labor union or not.5