Nos. 06-1358, 07-1060, 07-1087. Argued January 23, 2008. Decided March 14, 2008. On Petitions for Review and Cross-Application for Enforcement of an Order of the National Labor Relations Board. George Wiszynski, argued the cause and filed the briefs for petitioner, United Food and Commercial Workers, AFL-CIO. Steven D. Wheeless, argued the cause for petitioner, Wal-Mart Stores, Inc. With him on the briefs was Bennett Evan Cooper. Philip A. Hostak, Attorney, National Labor Relations Board, argued