Depends on the person I suppose.
if the person you've got side on from the neck down is wearing average street clothes, and has average build and no stand-out features such a missing limbs, tatoos, 8 fingers on their hands they're not identifiable... :-)
I know at least SS requires a release for people who are semi-nude at times, even if they are back-on. Such as women wearing bikinis. Probably easiest to post a thumbnail and we can all have a guess. ...