The Fruit & Vegetable Packers & Warehousemen, Local 760 (defendant), called a strike against fruit-packing companies that sold Washington State apples. To support the strike, the union picketed Seattle Safeway stores that carried the apples. The picketers wore placards and walked back and forth in front of the store entrances, passing out handbills urging customers not to buy Washington State apples. Beforehand, each store manager received a letter explaining the dispute with a copy of the instructions given to picketers, which forbade asking customers not to patronize Safeway. The National Labor Relations Board (NLRB) (plaintiff) found the picketing violated the National Labor Relations Act (NLRA), but the appellate court set aside the NLRB order. The Supreme Court granted review.