The reasons for permitting picketing to compel a closed shop even when none of the employees belong to the picketing union were articulated in C. S. Smith Metropolitan Market Co. v. Lyons: 'The members of a labor organization may have a substantial interest in the employment relations of an employer although none of them is or ever has been employed by him. The reason for this is that the employment relations of every employer affect the working conditions and bargaining power of employees throughout the industry in which he competes. Hence, where union and nonunion employees are engaged in a similar occupation and their respective employers are engaged in trade competition one with another, the efforts of the union to extend its membership to the employments in which it has no foothold is not an unreasonable aim.' The importance of attaining substantial equality in the economic struggle between unions and employers led to the conclusion that picketing to enforce a closed shop should be permitted notwithstanding possible injury to the employer or the nonunion worker.
Magill Brothers, Inc. v. Building Service Employees' International Union, and James v. Marinship Corporation, restated the law as established by the earlier cases, and in Park & Tilford Import Corporation v. International Brotherhood of Teamsters, it was declared once again, and without dissent, that under state law, considered alone, concerted activity for a closed shop is lawful even when undertaken by a union representing none of the employees. In Charles H. Benton, Inc. v. Painters Local Union, a decision handed down at the same time as our first decision in the present case, a majority of the court, obviously with the concurrence of those who dissented on other grounds, stated that, 'independently of rights given under the federal statutes, under California decisions an employer may not obtain relief from economic pressure asserted in an effort to compel him to sign a union shop agreement.' This proposition was not questioned by the majority in their earlier opinion in the present case.