I worked during the dialup years for a firm with an internet forum on one of their websites. A member of this forum was giving away the endings and major rug pulls to films. Think along the lines of who Kevin Spacey actually was in the Usual Suspects or Bruce Willis in 6th sense etc. However the day of or day after release not 6 months later when most people who wanted to would have seen the film. One studio complained and asked for this users IP address. Some forum members also complained.
The company checked with the ISP and they assigned IP addresses dynamically against a customer number. If the customer logged out a new Address was assigned even if they'd been gone a minute or so. This meant in theory they could identify the user but the bloke I spoke to said they would want a court order before doing the work to find out who it was and release it. We relayed this back to the UK arm of the studio concerned. To keep them happy we banned or blocked the user concerned and deleted their posts.
Studio lawyer said he was quite relieved as he had no idea what arguments he could take to court to convince a judge to issue an order. Not the crime of the century.