The Irish subsidiaries of EMI, Sony BMG, Universal and Warner are taking a case under copyright law. They say that Eircom is infringing copyright because its network makes available copies of music without the owners' consent.
The record labels want Eircom to filter the offending material out of its service, but Eircom will argue in Ireland's High Court that it has no legal obligation to monitor all the traffic on its network.
Eircom is the biggest broadband ISP in Ireland and is the former state telecoms monopoly.
Electronic rights pressure group Digital Rights Ireland (DRI) has condemned the court action and its chairman, a barrister, said that the case has no basis in Ireland's Copyright Act.
"ISPs are intermediaries. They are not, in law, responsible for what internet users do, any more than [the post office] is responsible for what individuals send in the mail," said TJ McIntyre, chairman of DRI. "In fact, European law specifically states that they may not be put under a general obligation to monitor the information they transmit."
DRI said that if the action was successful it would invade the privacy of internet users and make users pay the cost of monitoring themselves on behalf of private industry. It also said that filtering technology was not good enough and that it could interfere with legitimate internet use.
"This action undermines this principle and threatens the privacy of internet users – in much the same way as if [the post office] had to open and examine the contents of every letter they carry," said McIntyre.
There is growing international pressure on ISPs to tackle illegal file-sharing by users. France is introducing a trial of a system that forces ISPs to block infringing material this summer, while a Belgian court last year ordered an ISP there to filter traffic.
There are moves in Japan to filter traffic to weed out copyright-infringing files. Its four ISP representative organisations have said that their members will disconnect users found to be using file-sharing software to copy music and games illegally.
Trade body the Irish Recorded Music Association claims that music sales in Ireland are in steep decline and that this is a direct result of illegal file-sharing over the internet. It said that music sales in Ireland were €146 million in 2001 but only €102 million last year.
The UK Government has said that it will introduce a law forcing ISPs to disconnect illegal file-sharers later this year if the internet access and music industries cannot come to an agreement before then. The Government is believed to favour a system of staged warnings to users with a final sanction of disconnection for persistent file-sharers.