There was a "landmark" ruling this past week in Washington state, where the judge refused to accept an IP address as evidence in a case that a specific person had engaged in illegal file sharing. A list of network addresses was all they had.Fixed that for you.
He needs to stop stealing from everyone, not just her. Many times, these people have their own connections, but log in through other's networks to participate in illegal activity... Music and movie sharing, child porn, etc...
People are "smart" enough these days to avoid using their own traceable accounts for these activities because the RIAA, movie industry, and FBI are not shy about pursuit of violators.