Once a union has established majority support among a group of employees, the union’s right to represent those employees continues as long as the majority support continues. Employees can demonstrate they no longer want a union to represent them in a variety of ways. They can file a decertification petition with the NLRB to have an election conducted to see if the union still has majority support. Also, if a majority of the represented employees demonstrate clearly that they no longer want the union to represent them, such as by signing an uncoerced petition that was not initiated or supported by the employer, then the employer might be justified in no longer recognizing the union.
However, certain presumptions exist that protect a union for specified periods of time from any attack on their majority status. For example, the typical method by which unions establish majority support is in an NLRB-conducted certification election. If the union wins the election, the union enjoys an irrebuttable presumption of majority support for one year from the date the election results are certified. Also, if a collective bargaining agreement ("CBA") is signed between the employer and the union, the union enjoys a presumption of continued majority support for the length of the collective bargaining agreement, up to a maximum of three years. In two recent decisions, the NLRB reversed existing law in a way to give unions even greater protections from challenges to their majority support.