Simon Sinek has an excellent Youtube video about techniques of effective confrontation at work. He says that when you need to confront someone at work you must do three things, not necessarily in any order. You must state:
1. Specifically how you feel.
2. Specifically what they did (action).
3. The potential impact.
For example, “When you got up and walked out of the room on Thursday night, you made me feel completely humiliated. And, I fear that if this happens again I won’t trust you, that the love I have for you will be completely shaken.” And, if they become defensive, you repeat the whole thing again and then stop. It is designed to make people be accountable for their actions.
