Whilst many copyright holders do their best to pretend otherwise the law seems clear on the matter of who is responsible for any infringement.
http://cdn.ca9.uscourts.gov/datastore/opinions/2018/08/27/17-35041.pdfThe US supreme court judgement makes it clear that its not the ISP account holder simply because their name is on the ISP contract, infringement must be proved against a specific person and not simply the account holder, this fact alone may be used to stop a copyright industry fishing expedition when they have no idea whom the infringer actually is, most account holders will not (and should not) work as unpaid investigators for the copyright holders when threatened with all manner of ridiculous claims.
