Several online file-sharing sites have acted to curtail their exposure to allegations of copyright infringement after last week's shutdown of Megaupload.com, which U.S. authorities claim was responsible for music, movie and software piracy on a vast scale.
Filesonic and Fileserve, two "cyberlockers" which allow users to upload their digital files to be hosted in the so-called internet cloud, made changes to their sites over the weekend to prevent sharing of files beyond the original owner.
Such sites, whose rivals include Dropbox, Mediafire and Rapidshare, offer basic online storage services for free and then charge for extra capacity, just as Megaupload did before it was taken offline and its executives arrested.
Uploading and storing files in itself is not illegal but some users have been able to share copyrighted music and movies widely using such cyberlockers, without any revenues returning to content owners.
Filesonic, which is used by millions of people around the world, has disabled "all sharing functionality." "Our service can only be used to upload and retrieve files that you have uploaded personally," it wrote in a message on its homepage.
Fileserve showed a similar message to its hundreds of thousands of U.S. users, although it was not visible in other parts of the world.
Although there are varying legal precedents in the U.S. suggesting how far site owners can be held responsible for the actions of their users, several smaller file-sharing sites have also stopped rewarding customers who upload large amounts of content or direct traffic to their pages, as Megaupload is alleged to have done.
The U.S. Department of Justice's case against Megaupload is likely to hinge on how far prosecutors can prove that the site's owners and operators were aware of the scale of piracy on its network and encouraged it, or failed to respond to takedown requests by media companies under the US Digital Millennium Copyright Act.
Anonymous, the loose-knit hacking group which attacked several U.S. political websites, as well as those belonging to music and film companies in retaliation for Megaupload's shutdown, has now extended its "anticensorship" campaign to Europe.
The websites of the Polish prime minister, parliament and other government offices were left inaccessible following "denial of service" attacks, which were claimed by Anonymous. A Twitter account using the name AnonymousWiki had announced plans to attack the sites. (There are reports Anonymous will soon set up its own upload service.)
Poland is due to sign the Anti-counterfeiting Trade Agreement on Thursday and many Polish internet users fear this could curb freedom on the internet. It is seen as similar to the Stop Online Piracy Act in the US, which has unleashed a wave of protest from internet companies like Google and Wikipedia. Several Polish websites have pledged to "blackout" against ACTA on Tuesday, as some US sites did last Wednesday.
Following the attack by Anonymous, members of the Polish government met on Monday to discuss their stance on an international copyright agreement.
Following the governmental meeting, Michal Boni, the minister for administration and digitisation, said Poland still planned to go ahead with the treaty, as he said it would change nothing in Polish law. However, the government could now be faced with further disruption by disgruntled hackers.