The UK and 21 other European Union member states have signed the Anti-Counterfeiting Trade Agreement, better known as ACTA.

The countries signed the treaty, which aims to harmonise copyright enforcement across much of the world, in Tokyo on Thursday. However, the signatures of the EU member states and the EU itself will count for nothing unless the European Parliament gives its approval to ACTA in June, and digital activists have urged citizens to lobby their MEPs against voting yes.

Poland, which was one of the signatories, saw thousands demonstrate in the streets on Wednesday, protesting against the signing.

An EU diplomat also added his signature. However, five EU countries did not sign, namely Germany, the Netherlands, Estonia, Cyprus and Slovakia. Many other countries, such as the US, Japan and Australia, signed the document in September.

Although ACTA is primarily concerned with the enforcement of intellectual property rights (IPR), its designation as a trade treaty meant it could be negotiated behind closed doors. This lengthy process, led by the US and Japan, was exposed in a series of leaks — some via Wikileaks — that revealed what was going on.

The final version of ACTA is very different to earlier drafts, which would have forced countries to disconnect internet users if they were found to be repeatedly sharing copyrighted content. TheEU rejected this proposal, and other ideas, such as criminalising the use of a mobile phone camera in a cinema, also fell by the wayside.

The European Commission maintains that ACTA will not require any legal changes in the Union. It argues that the treaty will align IPR enforcement standards in other countries with those already enshrined in EU legislation.

“It simply does not change EU law,” trade commission spokesman John Clancy told ZDNet UK. “The freedom of the internet that existed before — people’s access and the way they use the internet — will not change because of ACTA.”

“The ACTA agreement is about trying to bring other key partners’ standards of intellectual property protection up to the level of the EU and other leading players in IPR,” he said.