A judge has raised concerns over copyright owners that attempt to take legal action against the registered account holders of IP addresses linked to illegal file-sharing activity.

Judge Birss made the comments during a ruling in the patent county court this week. He was presiding over a case in which a number of Brits were accused of downloading files illegally by legal firm ACS:Law and its client MediaCAT. However, prior to the judge's ruling, both ACS:Law and MediaCAT ceased trading.

"Does the process of identifying an IP address in this way establish that any infringement of copyright has taken place by anyone related to that IP address at all?" the judge asked during the ruling.

"Even if it is proof of infringement by somebody, merely identifying that an IP address has been involved with infringement [does not make it] clear to me that the person identified must be infringing one way or another. The fact that someone may have infringed does not mean the particular named defendant has done so."

Judge Birss added that using an unsecured network could potentially allow other web users to piggyback on the connection, which causes issues when trying to prove copyright infringement has been committed in court.

"What if the defendant authorises another to use their internet connection in general and, unknown to them, the authorised user uses P2P [peer-to-peer] software and infringes copyright?" he added.

Under the Digital Economy Act, a 'three strikes' rule will see web users thought to have illegally downloaded copyright-protected files issued with warning letters or emails. However, according to a spokesman for the Department for Culture, Media and Sport, "the measures in the Digital Economy Act (DEA) do not aim to attribute liability for online copyright infringement.  They aim to reduce and prevent such infringement". 

“Under the mass notification system internet account holders will be informed when infringement is happening on their account and given advice on how to prevent it.  The letters will aim to inform and will not ask for money," he said.

Last year, Ofcom drafted a code of conduct for the 'three strikes' rule but it isn't expected to come into force until later this year.

“The code, which is due to be published by Ofcom shortly, will require a robust standard of evidence and there will be a readily accessible appeals process," said the Department for Culture, Media and Sport.

“The Digital Economy Account and the code will not affect the standards by which courts make judgements about copyright infringement when rights owners seek to enforce their rights through the courts.”

Initially, ACS:Law had asked the judge to drop the cases. However, this is more complicated than initially thought, as the copyright holders were not involved in the legal action and could potentially continue to pursue the accused themselves. However, yesterday Judge Birss ruled the copyright owners have just 14 days to involve themselves in the cases, before they are dropped completely.

"Which? has always believed that ACS:Law had no justification for persecuting people on behalf of their client as illegal file sharers simply for owning an IP address. We're delighted that Judge Birss has supported this view today," said Deborah Prince, head of legal for Which?.

"This is the latest stage in our long campaign on behalf of those unfairly accused of illegal file sharing. Many people have suffered enormous stress after receiving a 'pay up or else' letter, and we hope this is the beginning of the end of such tactics."

See also: Legal firm to stop issuing net piracy letters