Due to a simple human error, over 8,000 legitimate websites—including Facebook and Google—were blocked in Denmark last week after mistakenly being labeled child pornography.

Instead of seeing sites normally, Danish users received a message. Translated, it read in part:

“The National High Tech Crime Center of the Danish National Police (NITEC), who assist in investigations into crime on the Internet, has [declared that the] page which your browser has tried to get in contact with may contain […] child pornography.”

The organization reportedly releases a daily, secret list to Internet service providers of sites that contain child porn.

NITEC chief Johnny Lundberg said that the person normally responsible for the list used a colleague’s computer, which led to the error.

In turn, Internet service providers use that list each day to block their users from visiting those sites. Two of Denmark’s minor ISPs, Síminn and Tele Greenland, adopted the day’s list before NITEC realized their mistake, and their users were unable to access a thousands of pages for over three hours.

Lundberg added that NITEC has already implemented a process where the list must now be approved by two employees, rather than just one.

That it’s so easy to black out sites on such grounds has rankled many Danes. The IT-Political Association of Denmark, a nonprofit citizens’ electronic rights group, was highly critical of the mistake.

“Apparently, the CP list can be updated by a simple file copying error, and this certainly casts the internal IT security of the Danish police into serious doubt,” the organization said in a statement.

It added that the mistake “seems to be a fairly simple human error, which because of extremely bad systems design escalated into something that can almost be described as a ‘kill switch’ for the Internet. Attempts to censor the Internet always create an artificial single point of failure.”

Photo by frankdouwes; edited by Kevin Collier