The Court of Appeal has overruled a trial judge's exclusion of evidence related to mobile phone masts which, prosecutors had claimed, would present ongoing difficulties in criminal trials.
The appeal with prejudice was taken following the directed acquittal of two persons for their alleged role in an historic crime.
Details of the persons and the alleged crime cannot be published as they are not presently charged with any offence.
The judge's ruling was made on the question of whether records from mobile phone masts could be relied upon to link individual phones to accused persons by placing them at relevant locations at relevant times.
In the first such application brought before the Court of Appeal since its inception, the Director of Public Prosecutions sought a declaration that the trial judge erroneously excluded compelling evidence.
The DPP also sought orders quashing the men's acquittals and that they be retried.
Giving judgment, Mr Justice George Birmingam said it transpired during the course of the trial that a particular mast may not have been the closest and original cell site through which a call was made if the original cell site was either too busy or not in operation.
The trial judge ruled the evidence inadmissible "in the absence of appropriate authoritative evidence to describe the function and operation of the system for the dates in question".
It seemed feasible, the trial judge ruled, for the prosecution to have such evidence available.
However, Mr Justice Birmingham said there was nothing to lead to a conclusion that the computer system was not operating as intended or that there was anything unreliable about the data recorded.
He said witnesses from Meteor and O2 were familiar with what the computer was required to do and were able to say it was doing it properly.
At most, it had not been established that there were not unsuccessful attempts to access one or more other masts. However, that was "quintessentially" a matter that went to weight rather than admissibility.
In that regard it was significant, Mr Justice Birmingham said, that the prosecution was not seeking to establish the precise location from which calls were made but the general direction of travel.
He said the Court of Appeal was satisfied that the judge erred in excluding the evidence in controversy. Having regard to the outcome of earlier trials, the court was also satisfied that it was compelling evidence.
Mr Justice Birmingham, who sat with Mr Justice Alan Mahon and Mr Justice John Edwards, will hear submissions on what orders should follow and in particular, whether or not a retrial would be appropriate, on 21 July.
Prosecuting counsel told the Court of Appeal in January that it had not been alleged that any of the accused were in a particular location but that they were in a general location.
Exactly where the calls were made had never been established, nor could it, he said.
If a call was routed through a particular cell site, the call wasn't made from the other side of the country, he said, but was made from within the cell site's coverage.
It was real evidence, he said, that those calls were made at that time and the conclusion to be drawn was a matter for the jury.
He said the judge extended the requirement necessary to adduce such evidence and had done so in error. If the error was not corrected by the Court of Appeal, he said, ongoing difficulties would persist and present themselves in criminal trials.
Responding to the prosecution, counsel for the defence at trial said there were two situations where the records could become unreliable and that was the problem.
The problem arose in relation to whether a mast was turned off and also whether the call was rerouted due to overloading.
The maintanence records of the cell sites were available for three years but appeared not to have been taken in time, counsel stated.
It was not a theoretical possibility, he said, but masts were turned off "not infrequently".
Evidence in relation to the operation of the system at the time was required at a minimum, he said.
The judge referred to the fact that this seemed to be a reasonable expection on the basis of what the evidence was and how it was presented. All the prosecution had to do was look at the records, counsel said.
The defence were hampered, counsel said.
Secondly, if the call was rerouted due to overloading then the call is sent to a cell with a weaker signal and one you wouldn't expect it to be sent to.
There had been extensive expert evidence dealing with the operation of the system and "these two glitches in the system" had to be explained away to the satisfaction of the judge who was in a unique position to see the importance of it, he said.
