Most employers of the late nineteenth century distrusted attempts by workers to organize and took active measures to hinder them. Among their tactics were:
★ the "yellow-dog" contract (a worker's agreement not to join a union during the period of his employment);
★ the blacklist (a list circulated among employers of workers reputed to hold opinions or engage in actions contrary to the employers' interests);
★ the injunction (an order issued by a court whereby one is required to do or refrain from doing a specified act) to restrain unions from actions harmful to employers;
★ the open shop (an establishment in which non-union members may work);
★ company police and company spies;
★ use of strikebreakers (called “scabs” by workers) to fill the jobs of strikers.