The music industry’s big four labels – EMI, Sony BMG, Universal Music, and Warner Music – decided to take Irish ISP Eircom to court today, in order to force the company to implement countermeasures against piracy.

Willie Kavanagh, Chairman of the Irish Recorded Music Association and Managing Director of EMI Ireland, blamed the action on a “dramatic and accelerating decline” in the Irish music industry’s income: 30% over the past six years, up to 2007. Kavanagh attributed a “substantial portion” of that decline to the increasing use of broadband, facilitating a sharp increase in the use of download services, like BitTorrent or LimeWire.

Sales dropped from €146m ($224m USD, not counting inflation) in 2001 to €102m ($157m USD) in 2007, said Kavanagh.

The case represents the first of its kind, with record labels taking the ISP to court instead of individual file-sharers. The big four’s High Court action attempts to compel Eircom, under the Irish Copyrights and Related Rights Act of 2000, to implement specific countermeasures to prevent its network from being exploited for piracy.

Eircom, one of the largest broadband providers in Ireland,  said last October that it was in no place to consider monitoring users, and noted that it had received no official notice of specific illegal activity; therefore, it was under no legal obligation to police traffic on its network.

Kavanagh said that Eircom was “well aware” that its network was being used for piracy, with infringers swapping the music industry’s intellectual property “on a grand scale.”

A recent study by UK-based law firm Wiggin found that piracy could drop as much as 70% if ISPs took an active role in monitoring users and threatening them with warnings; similar initiatives, seeing somewhat voluntary consideration by ISPs in the United States and elsewhere, have met with fierce resistance from customers, observers, and government authorities.