In NLRB v. Interboro Contractors, Inc., 388 F.2d 495, 500 (2d Cir. 1967), the Court of Appeals for the Second Circuit stated that the efforts of an individual employee acting alone to enforce the provisions of a collective bargaining agreement may be deemed "concerted," and thus protected, at least when the individual's interpretation of the agreement has a reasonable basis.
In Mushroom Transportation Co. v. NLRB, 330 F.2d 683, 685 (3d Cir. 1964), we held that to qualify as concerted activity "it must appear at the very least that [the conduct] was engaged in with the object of initiating or inducing or preparing for group action or that it had some relation to group action in the interest of the employees."
In N. L. R. B. v. Northern Metal Company, 440 F.2d at 884-85, the Court, branding the finding of "constructive concerted activity" in Interboro as a pure "legal fiction," said it was "unwilling to adopt such a fiction.
In N.L.R.B. v. Ace Comb Co., 342 F.2d 841 (8th Cir. 1965) and N.L.R.B. v. Bird Machine Co., 161 F.2d 589 (1st Cir. 1947), where instructions to supervisory employees not to make coercive statements did not relieve employer of imputed liability it is indicated that it might be otherwise if these instructions had been communicated to the employees.
In Shelly Anderson Furniture Manufacturing Co. v. NLRB, 497 F.2d 1200 (9th Cir. 1974), we identified the four elements essential to protected status of concerted activity.