High Court judges have banned police from bugging the legal consultations of a man held in connection with serious crime.
A direction was issued that officers cannot use covert surveillance against the suspect while he is in custody.
Neither the identity of the man nor the offence which he was arrested over can be disclosed for legal reasons.
His lawyers launched an emergency judicial review case in a bid to secure a declaration that no secret recordings were being carried out.
Barrister Karen Quinlivan claimed during the hearing that police conduct towards her client had been “oppressive and alleged officers have behaved unlawfully in the case.
The proceedings centre on a revised code of practice brought in under the Regulation of Investigatory Powers Act. In 2007 judges in Belfast ruled monitoring of solicitor-client consultations without authorisation was a breach of human rights.
But in the new case Tony McGleenan, for the Chief Constable, sought to defend the police position of neither confirming nor denying surveillance.
He told the High Court that six Surveillance Commissioners drawn from senior judicial positions were in place to oversee the controversial tactic.
Dr McGleenan said the Police Service of Northern Ireland is subjected to annual inspections.
He also argued that 12 safeguards have been put in place to satisfy privacy rights under European human rights legislation.
These include a pre-requirement for the Commissioners to authorise surveillance, and only in exceptional circumstances where there is a threat to life or national security.
Further tests involve establishing whether it is proportionate, and any material gathered cannot be used in criminal or civil proceedings.
Following two days of legal submissions Lord Chief Justice Sir Declan Morgan, sitting with Lord Justices Girvan and Coghlin, made an order preventing police from carrying out covert surveillance against Ms Quinlivan's client.
The case is to be mentioned again next week, when attempts may be made to bring the Secretary of State into proceedings due to his role in drafting the legislation.\[w.mcclelland\]Leave was also granted to seek a judicial review as part of the bid to gain assurances over the questioning process.