Police should not use taped interviews with suspects for voice analysis in investigations into unrelated offences, High Court judges have ruled.
Lawyers for a teenager facing charges linked to a bomb discovery in north Belfast said the verdict represented a significant prohibition on the practice.
Conal Corbett (19) was arrested as part of an investigation into a sophisticated device found at the junction of the Crumlin Road and Brompton Park in May last year.
Following his detention under the Terrorism Act, he failed to answer questions when interviewed by police.
Requests from his solicitor for an undertaking that any recording of his voice would not be retained for use in future investigations were refused by the PSNI.
Corbett, with an address at Flax Street in the city, subsequently remained silent on legal advice.
He is currently on bail charged with possessing articles and having documents likely to be of use to terrorists.
His lawyers launched a judicial review seeking a declaration that the PSNI's policy to record and retain suspects' voices was unlawful.
The court heard how a senior detective stated in an affidavit that police did not hold any other recordings of Corbett other than the interview tapes. However, files on a computer seized as part of the investigation contain samples of his voice.
The challenge centred on a codes of practice about audio recordings of those detained under the 2000 Act.
Delivering his judgment yesterday, Lord Chief Justice Sir Declan Morgan noted that an interpretation advanced on behalf of the PSNI was that tapes could be used for any police purposes. But he said: "Such an entitlement gives rise to the risk of arbitrary use absent of any conditions."
Sir Declan, sitting with Lord Justices Weatherup and Weir, preferred an interpretation about tape destruction, pointing to copies only being used for matters connected to the investigation on which the interview is based.
He concluded: "The interview working tapes retained under the audio code can only be used in criminal or civil proceedings related to the interviews conducted with the person. In light of this finding we do not consider it necessary to make any declaration."
Following the verdict, Corbett's solicitor, Paul Pierce from KRW Law, said that he had raised concerns over wider potential use of voice samples from crime suspects.
"This has had a detrimental impact on those people who, in certain circumstances, would speak to police during interviews," he added.
"This is a very significant finding where the court has said that the legislation and codes of practice do not permit the PSNI to do that."