Its simple.
You NEVER attack somebody as long as you're allied with them.
If the game settings are such that you can switch alliences (mostly used in phantom games) then you should break alliance with everybody you want to attack, before you attack them.
We need to enforce this, because people are ****** , especially when they are anonymous on the internet.
Just imagine getting bombed every teamgame by an ally and you should understand why this is necessary...
Attacking an ally can be understandable under some circumstances, but is simply never acceptable.
Whenever this does happen, the moderators need reports of it happening:
http://bit.ly/2a9Yg5i And they will take action.