The country's largest ISP introduced the graduated response system to combat illegal file-sharing as part of a legal settlement with EMI, Sony, Universal and Warner in Ireland.
The ISP started sending warning letters to suspected file-sharers with the threat of sanctions if the illegal activity continued.
Ireland's Data Protection Commissioner raised concerns over the procedure and ordered it be stopped altogether after evidence emerged that some warning letters had been sent to the wrong people.
But the major labels claimed that the notice would unwind their agreement with Eircom and, The Irish Times reports, argued that it was both unlawful and irrational to reopen data protection issues already determined by the courts in their favour.
As a result, at the Commercial Court yesterday, Mr. Justice Peter Charleton issued a judgment quashing the enforcement notice saying that it was invalid due to a failure on the commissioner's part to give reasons as to why it had been issued.
What reasons could be found, the judge said, "involved a misconstruction of the relevant law".
The Irish Recorded Music Association has said that it would press ahead with its campaign to implement a "three strikes and you're out" rule following yesterday's judgment.