American labor law as accepted and spread by the AFL-CIO of course remains in many ways a step back from even Gomper's voluntarism. There is a nice historical treatment in William Forbath's Law and the Shaping of the American Labor Movement (1991):
"many of the old common law restraints on collective action [have reasserted] themselves. The federal courts have interpreted the NLRA to prohibit virtually all forms of secondary strikes and boycotts, and the Supreme Court has upheld this bar against constitutional challenges. Even peaceful picketing urgin the public to boycott unfair goods is rountinely enjoined, and first amendment challenges are rountinely rebuffed. The persistence of amendment challenges are rountinely rebuffed. The persistence of these old restraints on labor protest seem anomalous today, when outside the labor context, both boycotting and peaceful picketing enjoy substantial constitutional protection. On its face, the refusal of constitutional protection for workers' boycotts and other protest activities would appear hard to defend. But labor protest occupies what one observer has called a 'constitutional black hole.' Courts continue to treat labor and labor protest on marketplace terms...See Pope...that labor is denied constitutional protections routinely extended to other groups because the courts treat workers as commodity sellers, regulation of whose activities is subject to rational basis review... The Gompers era idea that they had a distinctive place in the Constitution has left few traces. The old common law concepts rule from the grave. Labor remains a commodity in contemporary constitutional law."
p. 166
One thinks of how the UPS strike would have spread if secondary strikes and boycotts had been allowed!
yours, rakesh