Members of Poland's left-wing Palikot Movement wore Guy Fawkes masks - the universal symbol of anti-establishment dissent - in parliament to protest against the government signing an international copyright agreement that many fear will censor the web.
Poland signed the controversial Anti-Counterfeiting Trade Agreement (Acta) despite huge demonstrations in Warsaw streets and the hacking of governmental websites in a week of protests. Poland's Prime Minister Donald Tusk insisted that his government would not "succumb to blackmail".
Poland's ambassador to Japan, Jadwiga Rodowicz-Czechowska, signed the agreement in Tokyo and said Poland was one of several EU countries to sign. Others included Finland, France, Ireland, Italy, Portugal, Romania and Greece.
The US, Canada and South Korea signed the agreement last year.
Demonstrators fear that Acta will be as pernicious as Sopa, the Stop Online Privacy Act, would have been had it not been withdrawn by the White House and the US Senate after a mass protest by hundreds of major user-generated content websites.
Some musicians, however, support the new law. Polish rock start, Zbigniew Holdys, has come out in support of Acta and accused| internet activists of profiting from pirated online material online at the expense of artists.
According to the Electronic Frontier Foundation (EFF), the bill will deal primarily with counterfeit physical goods such as medicine but experts claim it will have broader scope and will deal with new tools targeting "internet distribution and information technology".
The Polish branch of hacker collective Anonymous has attacked Polish government websites, including the prime minister's office, leaving several paralysed. Tusk posted a '10 myths about Acta' article on its website, saying the agreement is in line with international trade law.
Dutch MEP Marietje Schaake posted a statement on Reddit that said: "I am concerned about the Acta treaty in the international trade committee. The internet blackouts by thousands of websites in protest [against] the Stop Online Piracy Act and the Protect Intellectual Property Act (Pipa) have raised lively discussions."
Anonymous is poised to attack the Polish government again, reports have suggested.
"ALERT: #ACTA Will Be Signed by UE & US tomorrow - EXPECT US! Are you going to stay quiet? Say NO to #ACTA!" reads a tweet from the @Anonops Twitter account,