In the past what I've seen is that the police will ask you to identify who was using an IP and also to help them catch the person in the act if they do the thing again. So far I haven't seen them get too pushy if you can't do the first thing as long as you're willing to do the second.
> In the past what I've seen is that the police will ask you to identify who was using an IP and also to help them catch the person in the act if they do the thing again
What's the method to catch the person in the act? Is it something like creating a rule: "if [this website] was visited between [foo] and [bar] notify me" at the routing level?
Let the majors/govs do the work of spying and detecting piracy / illegal websites, and just answer to subpoenas, that will be enough.