In not just one recent case, but two:
* “During a meeting about commissions, minimum wage, and employee breaks [at a Yuma, Ariz. car dealership], an employee lost his temper, angrily calling his supervisors words such as [obscenities omitted]. He also stood up, shoved his chair aside, and told them they would regret it if they fired him. Unsurprisingly, that tirade resulted in the employee’s termination. Astoundingly, in Plaza Auto Center (5/28/14), the NLRB concluded that the termination was an unlawful violation of the employee’s rights to engage in the protected concerted activity.” [Jon Hyman, Ohio Employer's Law Blog; Brennan Bolt, Labor Relations Today]
* “Starbucks cannot fire a union activist employee who cursed at a manager in front of customers, the National Labor Relations Board has ruled for the second time. Joseph Agins was active in trying to unionize four Manhattan Starbucks coffee shops between 2004 and 2007.” His repeated imprecations, sometimes in the presence of customers, included “this is [BS],” “do everything your damn self,” “about damn time” when the manager arrived to help, and “go … yourself”. A protected pattern of behavior under federal labor law, the NLRB ruled. “The board ordered Starbucks to offer Agins his old job or a substantially equivalent position, compensate him for any loss of earnings and other benefits, and remove from its files any references to the unlawful firing.” [Seattle Post-Intelligencer]
Compare the separately developed field of “hostile-environment” law, in which the employer may be held liable for years’ worth of back pay if it does not separate from the workplace an employee who repeatedly confronts a co-worker with belligerent and profane abuse (& Scott Greenfield).