My understanding of most filesharing lawsuits initiated by copyright holders is as follows:
- The monitoring agency will connect to a torrent swarm and collect the ip addresses of people downloading files to which they hold the copyright
- They identify the ISP's to which theses ip addresses belong and subpoena them for the identities of the end users in order to initiate legal proceedings against them directly.
What I'm wondering is if a 3rd party could legally start with your name and work backwards to find out if used Bittorrent or p2p. Let's say you're a public figure and they're looking for dirt. Wouldn't you need probable cause first?
Does it get more complicated if the person uses a secure vpn? Are there shortcuts that the 3rd party organization could take to gather p2p usage data without having to subpoena the ISP or vpn provider?