Optimal is nice aggression: push forward for the goal in the nicest way possible, and resort to more confrontational style only when absolutely necessary.
Being justified in a social setting means other people need to agree with you.
It involves directly addressing the matter at hand; why it is you are justified in confronting somebody. It can also be tactful if you get the person you are confronting to be very specific on the details and why they did something worth being confronted about.
The crowd will decide on their own, but if you truly are justified in confronting somebody then you should have solid foundation for debate.
Now, certain crowds practice mob justice, but that's another thing entirely.
