If management asks you to attend a meeting that you fear may lead to discipline, here’s what you can say:
“If this discussion could in any way lead to my being disciplined or terminated, or affect my personal working conditions, I respectfully request that my union representative or steward be present at this meeting. If I am denied my right to have a union representative present, I will refuse to answer accusatory questions and any questions I believe may lead to discipline.”
Weingarten was a 1975 Supreme Court decision affirming that employees have a right to union representation at investigatory interviews.
More details on Weingarten rights may be found here on the SEIU 503 website.