Thirty defendants charged with a raft of offences when police busted an encrypted phone network were left reeling after senior judges in England refused to throw out evidence in their cases.
In a ruling delivered at the Court of Appeal in London, Lord Chief Burnett of Maldon, Lord Justice Edis and Mrs Justice Whipple ruled that messages accessed by French police through the cracking of the Encrochat network were not obtained through interception.
Had the ruling gone otherwise, the messages would have been inadmissible.
The National Crime Agency (NCA) previously described the cracking of the network as the biggest ever breakthrough in the fight against organised crime.
Around 1,000 people in England are facing charges linked to the massive investigation, named Operation Venetic.
The PSNI, working alongside the NCA, brought charges against 30 men in Northern Ireland.
These include conspiracy to murder, conspiracy to import cocaine and cannabis, money laundering and firearms offences.
Among the suspects are:
The suspects were charged separately, but the police and NCA believe they can prove each man is involved in organised crime through messages obtained via the cracking of Encrochat.
While judges in England ruled the messages were not obtained through interception, the decision is not binding on local judges.
Patrick Madden, whose law firm Madden & Finucane Solicitors represents the majority of local defendants, warned that further legal arguments would be pursued.
The cases "urgently require a rigorous and thoroughly independent level of judicial scrutiny," Mr Madden said.
"Whilst we are disappointed that the English Court of Appeal has dismissed this appeal and ruled in favour of the admissibility of this evidence, there are further legal challenges on the horizon.
"In particular, there are grave concerns over the lack of transparency in the secretive breach by French authorities.
"We are giving full and urgent consideration to the contents of the English judgment.
"We have grave and fundamental objections in respect of how this material was obtained.
"We consider it (to be) improperly and illegally obtained evidence.
"We are looking forward to the challenges that need to be litigated as a matter of urgency, given the ruling in London."