In addition, I believe it is not in your company’s best interests to voluntarily share with employees that they have the right to coworker
participation. Whereas Weingarten rights have been around for union employees for twenty-five years, this new interpretation for nonunion employees is untested.

In addition, coworkers in general—unlike union stewards, who are trained in basic employee relation principles and practices—may not understand the fundamental rules of management intervention. As a result, unqualified ‘‘coworker’’ involvement may create problems in sensitive investigations. By expanding the ‘‘need to know’’ circle, the coworker’s presence creates a greater chance of loss of confidentiality or breach of privacy.

This new interpretation of Weingarten constitutes a substantial change in the law and imposes additional duties on nonunion employers. The case is on further appeal as of this writing, so it’s best to check with qualified legal counsel whenever a nonunion employee requests the presence of a coworker at an investigatory meeting that could result in discipline.

Taken From : The Hiring and Firing Quention and Answer Book