Those same rights do not extend to a non-union setting. In IBM Corp. (June 9, 2004) [pdf], the National Labor Relations Board concluded that “the right of an employee to a coworker’s presence in the absence of a union is outweighed by an employer’s right to conduct prompt, efficient, thorough, and confidential workplace investigations.” While the holding only mentioned a coworker representative, the employer had denied the employee’s request for a coworker or an attorney to be present.
It is important to note, however, that the federal courts and the NLRB have gone back and forth on this issue over the years, and that IBM was a tight 3-2 decision of a Bush-appointed NLRB. Even the IBM majority recognized that one could reasonably interpret the National Labor Relations Act to reach the opposite conclusion. Because President Obama has already appointed a new Chairperson, and will fill three other vacancies on the NLRB, there is a good chance this rule will change if the issue makes its way back to D.C. in the next three years.
For now, employers are well within their rights to prohibit employees from having representation during investigatory interviews or disciplinary meetings.