In NATIONAL LABOR RELATIONS BOARD v. WASHINGTON ALUMINUM CO. we look at what constitutes a concerted action, in accordance with NLRA Section 7.
The case pertains to an aluminum manufacturing factory in Baltimore, MD in the late 50s that in the winter time was extremely cold. At times to the point of inhospitability(I think I made that word up). There are a number of workers in the factory, that from time to time complain to their supervisors about the cold, and how difficult it is to work.
One extremely cold morning they are complaining to a supervisor who says “if those fellows had any guts at all, they would go home.” Shortly thereafter, they decide to leave. 7 of the 8 workers leave, the 8th was about to leave, but was somehow coerced into staying.
There is a company policy that forbids employees from leaving the facility without permission. The workers are fired for violating said policy. They sue, NLRB finds in their favor, stating that their protest is a concerted activity in accordance with Section 7 and that they should be reinstated and given back pay.
On appeal, the decision is upheld. While there is no organized union, or notice that they were specifically “on strike” the actions were permissible under Section 7 and protected as actions in concert. They did complain on several occasions to the employer, specifically about the working conditions, and nothing was done to remedy them. They then, in concert, decided to leave due to the extreme cold.