An interesting avenue of doubt seems to have opened up during a recent case brought against an alleged filesharer in Germany.
https://torrentfreak.com/court-warner-bros-needs-stronger-evidence-against-alleged-bittorrent-pirate-170718/In Germany, several major Hollywood studios are actively pursuing alleged BitTorrent pirates, charging hundreds of euros for illegally downloaded movies and TV-shows. While this is common practice, a local court recently clarified that the copyright holders must provide solid evidence if they want their claims to hold.
In this case, the defendant argued that his ISP failed to update the IP-address assignments and that he no longer used the infringing address at the contested time.
The District Court of Cologne agreed that this was a plausible argument. Ideally, Warner should have provided a more extensive tracking record, with more IP-addresses leading to the same account holder, assuming that the assignments regularly change.
Common sense still prevails