There may or may not be any relevant legislation, but sure as hell it will be part of your ISP's T&Cs. They've got their own backsides to cover.... nested quotes trimmed ...Indeed. The owner of the line is 100% responsible for what happens on it and so if someone was to access any dodgy (illegal) sites then you could have a knock on the door and unless you have some very good logging it would be difficult to prove the neighbour was responsible. Effectively if you share your connection you need to consider ISP level logging to protect yourselves in the event of an issue.
Sorry, but could you provide some sort of reference to legislation that makes this the case?
I get that suspicion would likely fall on the subscriber in the first instance, but I'm pretty sure that doesn't mean they are responsible for the criminal acts of others.
If I were the neighbour being asked I'd be rather wary given that the police can and do simply come in and take every part of a suspect's computer (including keyboard, monitor, mouse etc.) rather than just the storage items and, no doubt, keep them for months, years or forever.
It was precisely because of all the confusion above that I decided the best way might be hacking rather than asking my (friendly) neighbour! In the event I didn't need to attempt it as my internet wasn't cut off.
Although I've not read mine I'm very sure the ISP's T&Cs will ban sharing - they have profits to consider!