They say
“You can’t tell me what to do.”
Your response
“Let’s clarify that before we go further. My understanding is that this decision is mine to make. If that isn’t clear from our roles, we’ll verify it before we discuss the task.”
First, check this
Do you actually have authority over this person and this decision, and is that authority clear in the reporting or matrix structure?
Why this works
A manager should not answer an authority challenge with rank before checking whether the authority is real. Matrix, project, and dotted-line relationships can leave decision rights genuinely unclear. Stating the manager’s understanding without declaring it unquestionable keeps the conversation calm and makes verification possible. Once authority is clear, the discussion can move to the specific task. That is different from arguing about friendship or demanding personal loyalty.
Don’t say
“I’m your boss, so yes, I can.”