Appeals court blocks government rule on union posters WASHINGTON - A federal appeals court has temporarily blocked the National Labor Relations Board from making millions of businesses put up posters informing workers of their right to form a union. The U.S. Court of Appeals for the District of Columbia issued a temporary injunction Tuesday. The rule was supposed to take effect on April 30, but a three-judge panel says that can't happen until legal questions are resolved. The order comes after a federal judge in South Carolina last week ruled the labor board exceeded congressional authority when it approved the poster requirement last year. Another district had said the rule was acceptable. Business groups claim the posters are too one-sided in favor of unions.