In 2017, Tesla enacted a clothing policy that only allowed workers to wear black t-shirts after unionization efforts began at one of its facilities. However, on Monday, the NLRB ruled in accordance with Supreme Court precedent and decided that Tesla could not prohibit workers from wearing clothing with union symbols. The United Autoworkers Union has responded by calling the decision a victory, but it has also expressed displeasure in the lengthy time it took for the decision to be made. The NLRB also recently reversed a 2019 decision that allowed Walmart to restrict union apparel in a similar effort to better align with precedent and protect employees' rights under the NLRA.
See "NLRB rules Tesla violated labor laws by banning workers from wearing pro-union apparel", Reuters, CNN Business, August 30, 2022