Both the ACGME and institutions themselves have specific policies and procedures in place for residents to file formal complaints regarding a number of different things. This can include a grievance against a disciplinary action or in relation to the working environment they are in. As a first step, unless they are directly involved, residents are typically required to have a discussion with the residency program director first. Once a formal grievance is filed, the PD gets involved by reviewing the complaint and working to submit necessary materials to any further governing bodies. Your interviewers ideally want to hear that you will maintain a fair and just process with the resident, keeping their interests in mind, while also letting processes fairly play out as outlined in policies.
