Five record companies have lost a case against UPC in a bid to force the internet service provider to stop internet users downloading copyrighted material.
UPC is the third largest internet provider in Ireland, with 15% of the market.
The Irish Recording Music Association wanted a High Court injunction so that UPC would have to prevent the theft of their copyright by its subscribers.
But Mr Justice Peter Charleton ruled that there is no provision for the blocking, diverting or interrupting of internet communications intent on breaching copyright.
The injunctive relief was declined.
A spokesperson for Eircom has said the internet service provider will be considering its position in light of today's ruling.
Eircom has a voluntary agreement to provide record companies with the IP addresses of customers involved in file sharing.
It also operates a 'three strikes and you're out' rule, so if customers are caught illegally sharing files online, more than three times, they will be disconnected for a year.
UPC has said it does not condone piracy, but today's ruling supports the principal that internet service providers are not liable for the actions of their customers.
Meanwhile, Minister for Communications Eamon Ryan intends to invite representatives from the music industry and internet service providers into his Department to formulate an agreed approach on peer-to-peer filesharing.