In the UK, rightsholders have the power to demand arbitrary censorship of websites they dislike, and ISPs are required to block those sites. The Premier League -- the multibillion-dollar football organization -- carelessly added the IP address of a major web-host to its censorship list, and as a result blocked The Radio Times (the BBC's former listing service now operated by a private company), Galaxy Zoo (an important astronomical research project), and many other legitimate sites. People who tried to visit those sites instead saw a warning saying that the sites were devoted to copyright infringement and that anyone visiting them was also infringing copyright.
ISPs were flooded with complaints, and began to unblock the sites themselves. But the Premier League is outraged at this. They say that even if the Premier League censored the wrong sites, it isn't up to the ISPs to uncensor them -- the ISPs are supposed to comply with the lists they get from rightsholders, no questions asked.
The way the system works is that the rights-holders are responsible for identifying which IP addresses are being used and then sending the details to the ISPs.
The court specifically said that ISPs are "wholly reliant" on the rights-holders "accurately identifying" which IPs should be blocked and had "no obligation" to check them themselves.
In addition to Radio Times, several football clubs - including Blackburn Rovers, Reading and Brentford - as well as the Notes from Nature science project and Galaxy Zoo space education site have been affected...
... "The court order that requires internet service providers to block this website clearly states that any issues they have in implementing the block must be raised with the Premier League before taking any further action," said a spokesman.
"This is the first we have heard of this issue and are looking into it as a matter of urgency.
"The fact remains that the High Court has ordered an injunction requiring ISPs to block First Row Sports and we will continue to implement it and expect the ISPs to respect the ruling."
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.