R v Karaali (No 5) [2023] NSWSC 233

Supreme Court New South Wales

Medium Neutral Citation: R v Karaali (No 5) [2023] NSWSC 233 Hearing dates: 27 February 2023 Date of orders: 27 February 2023 Decision date: 27 February 2023 Jurisdiction: Common Law Before: Campbell J Decision: Prosecutor's question to expert witness Mr Chang regarding congestion of the telephone network is allowed. Catchwords: EVIDENCE — expert evidence — whether opinion within expertise Category: Procedural rulings Parties: Rex (Crown) Abdul Karaali (Accused) Representation: Counsel: P Hogan (Crown) IH Wallach (Accused)

Solicitors: Director of Public Prosecutions (NSW) (Crown) TNL Law (Accused) File Number(s): 2020/61211 Publication restriction: Not to be published until the completion of the trial

eX tempore JUDGMENT 1. Mr Chang, an electrical engineer employed by Optus in a senior position in relation to the operation of the mobile telephone network conducted by that company in New South Wales, is giving expert evidence before me in relation to the operation of the system. The issue to which the matter goes relates to the extent to which the connection of a mobile device with the signal emitted by a particular mobile base station says something about the probable geographical location of the device. His evidence establishes that the system operates on the premise that a device will connect with the strongest available signal. Usually, that will be the closest geographically, but not always, and that consideration can be affected by a number of different factors which I need not traverse here. The focus of the current debate is about the evidence that Mr Chang gave that congestion of the business of a particular base station may affect the strength of this available signal, effectively, but not literally, diverting a mobile that might otherwise be within its footprint to another more remote, in relative terms, base station. 2. Mr Chang has been cross-examined about that in some detail by Mr Wallach of counsel for the accused. He has freely conceded that to be definite about whether there was or was not congestion of a particular base station on a given occasion, one would need to — my expression — go back and crunch the numbers that would be available in Optus's records, and he has not done that spadework. 3. In re-examination by the learned Crown Prosecutor, Mr Chang initially gave evidence on that topic by reference to the carrying capacity of a single antenna in the system as at 14 February 2020 in quantitative terms. In answering that question, he did volunteer that in his opinion it was unlikely that a particular antenna would be overloaded by the amount of traffic on the particular occasion. I rejected that additional comment because it was unresponsive to the particular question he had been asked. Mr Crown followed up with a question which sought to elicit that opinion and Mr Wallach objects to it. 4. The evidence he wished to give was obviously a matter of opinion and, in my judgment, is an opinion within his expertise by reason of what he has described of his training, study and experience because it goes to, fundamentally, the carrying capacity of a given antenna and his own knowledge of the operation of the network over a period of 25 years. To my mind, the opinion that he wishes to express is not inconsistent with the evidence he has already given to Mr Wallach. There is no doubt that the only way to be sure about whether or not there was congestion is to crunch the numbers. But that does not render Mr Chang's opinion inadmissible. It would certainly affect its weight, or at least would be capable of affecting its weight, but matters of weight, of course, are matters for the jury and not matters of admissibility. The question of whether the jury are prepared to accept the expression of opinion, in circumstances where the spadework has not been done to quantify the actual traffic on the occasion in question, is a matter for them and not for me, and I am of the opinion that the question sought to be asked is not objectionable. I will allow it.