Employees at a Starbucks in Manhattan were attempting to unionize and part of their efforts involved wearing pro-union buttons as part of their uniform. Starbucks limited the amount of buttons, or, flair, that the employees could wear to one button and an unfair labor practice complaint was filed with the National Labor Relations Board (NLRB). The NLRB ultimately held the limitation to run afoul of the National Labor Relations Act (NLRA) but the Court of Appeals for the Second Circuit has reversed this decision holding that, just as it can require employees to "wear buttons promoting its products, ... it is also entitled to avoid the distraction from its messages that a number of union buttons would risk."
This decision essentially holds that an employer's interest in having employees promote their product outweighs the employees' interest in promoting unionization. The case is NLRB v. Starbucks Corp., Case Nos. 10-3511-ag, 10-3783-ag(XAP) (2nd Cir. May 2012).