A friend of mine was the victim of a physical assault resulting in a black eye and a residual small scar. The person who punched them has made an allegation that my friend broke their tooth. Basically he fell off a stool at a party when everyone was laughing at a joke then jumped up and punched my friend who had been sitting beside them in the face, damaging their glasses and leaving them with a nasty bruise and cut. There is a witness statement confirming this but my friend told the police at the time of giving his statement that maybe he bumped off the other guy when they were laughing and joking but that he wasn't sure. Can my friend also be charged with assault?