When do employees have a right to request a union representative? 

An employee’s right to request a representative arises during an investigatory interview.  A useful comparison is an individual’s Miranda right to an attorney when questioned by law enforcement.  However, unlike the right to counsel in a Miranda setting, employers are not required to inform union members of their rights under Weingarten.

Any meeting may be an “investigatory interview” provided that the following occurs:

• A manager, representative of management, or supervisor is seeking to question an employee.  
• The questioning is part of an investigation into the employee’s performance or work conduct.  During an investigatory interview, a representative of management may require an employee to defend, explain, or admit misconduct or work performance issues that may form the basis for discipline or discharge.  
• The employee reasonably believes that the investigation may result in discharge, discipline, demotion, or other adverse consequence to their job status or working conditions.  
• The employee requests a union representative.  Employers are not required to advise employees of their right to representation and third parties (including union representatives) may not make the request on behalf of the employee.https://apwu.org/weingarten-rights