Prior to 1947, employees once represented by a union could not return to nonunion status. With the passage of the Taft-Hartley Act in 1947, the National Labor Relations Board acknowledged for the first time that it could entertain "that negative type of representation proceeding, known as a 'decertification' case." Has decertification had a negative effect on collective bargaining or the labor movement? The number of decertification petitions and elections is increasing, and unions are winning a decreasing percentage of these elections. But the growth in decertification is less a national phenomena than one might think.