Originally Posted by HarryT
an ISP can determine which customer that IP address was allocated to at a specific time.
So besides the fact that you have no idea who was using a given computer at what time (it might even be hacked), now you are asking ISPs to keep perfect records of who was doing what at which time, and hand them over based on the vague allegations of a bunch of wannabe monopolists? How specific do these allegations need to be, or should we just hand those logs over to anyone who asks (not to mention the discussion of whether these logs should be kept in the first place?). And are these logs sacred, i.e. can they never be altered or corrupted or misread? We're talking about ISPs here.
Why not just kill privacy altogether? It won't stop piracy, it will merely force it deeper underground using heavy crypto and semi-closed networks, or some other tech I can't envision with today's knowledge. Or just the good old hard drive swap.