Oh and btw, Leia says “When they hear you’ve attacked a diplomatic…” -> it is pretty clear the Empire attacked if you still think that Tantive IV shot first (maybe they can make a Special Edition about that) or that there would be a chance to welcome them aboard.
Well and my point is that Tantive IV did not need to shoot first in order to justify Empire’s action. The rebels probably refused to be stopped by the star destroyer (official authority). It is like running away when the cops try to stop your car. When they chase your car after that, you deserved it.