To ensure that employees are effectively able to bargain for a collective agreement, the NLRA 1935 created a group of rights in §158 to stall "unfair labor practices" by employers. These were considerably amended by the Taft-Hartley Act of 1947, where the US Congress over the veto of President Harry S. Truman decided to add a list of unfair labor practices for labor unions. This has meant that union organizing in the US may involve substantial levels of litigation which most workers cannot afford. The fundamental principle of freedom of association, however, is recognized worldwide to require various rights. It extends to the state, so in Hague v. Committee for Industrial Organization held the New Jersey mayor violated the First Amendment when trying to shut down CIO meetings because he thought they were "communist". Among many rights and duties relating to unfair labor practices, five main groups of case have emerged.

The Norris-LaGuardia Act of 1932 outlawed the issuance of injunctions in labor disputes by federal courts. While the Act does not prevent state courts from issuing injunctions, it ended what some observers called "government by injunction", in which the federal courts used injunctions to prevent unions from striking, organizing and, in some cases, even talking to workers or entering certain parts of a state. Roughly half the states have enacted their own version of the Norris-LaGuardia Act.