My learned friend, what kind of tort are you talking about? Go and dig deeper, there are precedents which may make an adjudicator dispense with such a general rule. Furthermore, the complainants were the ones needed to prove, the insulted person was just to be a witness needed not to prove damage on herself rather than proving the words were uttered. There was no need of calling her if the evidence adduced sufficed to convict the way the complainant contemplated. For example if I utter abusive words to your father at your presence, will you fail to prove damage or injury upon yourself? As you will be the complainant, your father's role will be to prove that there were such abusive words. Scout around my fellow learned friend.