The test of fairness is whether you still support the principle after changing places.

Any principle should survive a change of seats. If it looks right when you are the one enforcing and wrong when you are the one subject to it, then what you hold is a position, not a principle, and it will not persuade anyone who is not already on your side. The swap is the whole test.

Run it deliberately on something you are currently arguing about. Argue the other side for five minutes as though you meant it, and see what still stands.