They signed up with ten providers and put online a work by Dutch author Multatuli, who died over 100 years ago. They stated that the work was in the public domain, and that it was written in 1871. They then set up a fake society to claim to be the copyright holders of the work.
From a Hotmail address, they sent out complaints to all ten of the providers. Seven out of ten complied and removed the site, one within just three hours.
Only one ISP actually pointed out that the copyright on the work expired many years ago.
The conclusion of the investigation is worth reading, it starts
It only takes a Hotmail account to bring a web site down, and freedom of speech stands no chance in front of the Texan-style private ISP justice — via boingboing