Graham Dwyer has won his legal action against the State and the Garda Commissioner over the use of mobile phone data during his trial.
The former architect was convicted by a jury three years ago of the 2012 murder of childcare worker Elaine O’Hara.
Mobile phone data formed a huge part of the trial but Dwyer argued it shouldn’t have been used as it breached his rights.
The High Court has ruled that Irish laws - which allow for mobile phone data to be retained and accessed - breaches EU law.
Dwyer wasn't in court for the ruling, but his father was.
Today's ruling will now form part of his appeal against his conviction for Elaine O’Hara’s murder.
A date for that appeal hasn’t been set yet.
