An indian man was wrongly detained for 50 days when his ISP reported the wrong customer for an IP given to them by the indian police.
Apparently, the police were tracing the poster of an unflattering image of a historical figure, so they contacted Google, who obligingly supplied the IP.
The police then contacted the ISP, who provided the name and address. Trouble is, they supplied the details of the wrong person.
Now, this is where it gets surprising. Once they had caught the actual perpetrator(s), the police took 3 weeks to release him.