Edit: Reference was made to R v Edwards when the Court of Appeal refused to grant a permanent stay in Wells v The Queen  VSCA 100. It was argued that the accused suffered an irreparable forensic disadvantage in defending a charge of culpable driving the vehicle he’d been driving having been scrapped.
Ashley JA [beginning at 22]:
22 In the present case, I am not at all persuaded, as matters presently stand, that the destruction of the vehicles, most particularly the utility, constituted circumstances which would justify grant of a stay. Whilst the applicant was deprived of the opportunity of having his expert examine the vehicles, the examiner’s conclusions, based upon his inspection of them, are not challenged. Further, it appears to me to be quite improbable, as matters stood at the end of the evidence of the examiner and Mr Marshall on the voire dire, that examination by the latter could have provided evidence of a defect which could explain the collision. I consider also that the applicant is by no means deprived of a forensic answer to the examiner’s evidence. Again, the trial judge could no doubt seek to redress any disadvantage faced by the applicant by an appropriate observation.
23 I should add this: The police did no more than release the utility to its owner. It was not the police who destroyed it, or gave instructions for its destruction. Indeed, it was common ground that the police followed ordinary practice in returning the vehicle, after inspection, to its owner.
24 Counsel for the Crown nonetheless accepted that, in the particular case, it would have been better had the police retained the vehicle. I agree. It was pertinent that – (1) the owner of the utility was someone other than the applicant; (2) the police were apparently on notice, before the vehicle’s release, that the applicant was asserting that he had no recollection of the incident; and (3) the circumstances of the incident were, on their face, unusual. But to say that a different course would have been the preferable course is not to say that the course which was followed requires grant of a permanent stay. I do not accept the submission that the conduct of the police was such as to bring justice into disrepute.
Application had been brought by the accused under s 296 of the Criminal Procedure Act. His application was refused and the matter returned to the County Court for the trial to continue.
Both cases were then applied in El Bayeh v The Queen  VSCA 44, a case where drugs were destroyed prior to trial. The Court of Appeal ruled the prejudice was only potential, and not actual, and dismissed the appeal.
The High Court yesterday delivered its judgment in R v Edwards  HCA 20, deciding that a prosecution of two airline pilots should not be permanently stayed though evidence was lost and the prosecution was unjustifiably delayed.
The respondents were the captain and first officer of a Qantas jet operating in and out of Launceston airport at night on 23 October 2001.
The air traffic control tower wasn’t staffed late at night, so the pilots had to turn on the runway lights using the Pilot Activated Lighting System, a nifty remote control in their plane.
A couple of workers at the airport complained to the Civil Aviation Safety Authority (CASA) and Air Transport Safety Bureau that the aircraft took off when the runway lights were off — an offence contrary to the Civil Aviation Act 1988.
CASA investigated and referred its investigation to the Commonwealth DPP, but the prosecution didn’t commence until 30 March 2004.
By the time that prosecution commenced, two pieces of important electronic evidence were gone.
The first was a monitoring record of activations at the airport of the Pilot Activated Landing System.
The second was the aircraft’s Flight Data Record. (That’s the black box we often hear about in aircraft crashes — thought it’s actually bright orange!) The FDR recorded radio transmissions from the aircraft — such as would have been used by the Pilot Activated Landing System to turn the runway lights on. The FDR data wasn’t recovered in the 15 or so days it was retrievable after the incident, and was then overwritten and lost forever.
The pilots contested the charges, and the judge at first instance stayed the charges because of the delay, and loss of the evidence.
In a joint judgment, the High Court found:
 An essential element that the Crown must prove in support of the principal and alternative counts is that the runway lighting was not on at the time the aircraft moved along the runway and took-off. The lost evidence goes to this issue as does the testimony of witnesses whose accuracy and reliability may be affected by delay…
 His Honour had earlier concluded that the delay alone would not warrant a stay of proceedings. He distinguished between the delay to the date the complaints were laid and the subsequent delays associated with the court proceedings. However, his ultimate conclusion was based upon the loss of the primary evidence and “overall” delay. It was not explained how the overall delay operated in combination with the lost evidence to create irremediable prejudice to the respondents, nor did his Honour address the circumstance that at least some of the delay was attributable to the conduct of the defence. On the appeal the respondents do not rely on the overall delay but maintain that the unexplained delay of two years and three months before the complaints were laid occasioned prejudice in that they had lost the opportunity to obtain the early recollection of witnesses. It is to be noted that the respondents were on notice of the allegation not later than 2 January 2002.
 The respondents do not contend that the loss of objective evidence, such as electronically recorded data or the like, would ordinarily justify a stay of proceedings on indictment. In the course of argument the respondents conceded that the loss of film recorded by a closed-circuit television camera at the scene of an alleged offence would not afford a basis for a stay. They seek to distinguish their case on the basis that the loss here is of the independent record of the event giving rise to the charge. This is said to be productive of unfairness of the kind that informs the power to stay since the trial will necessarily involve an incomplete reconstruction of the event.
 The distinction between an independent record forming a constituent part of an event and an independent record of an event is without substance. Trials involve the reconstruction of events and it happens on occasions that relevant material is not available; documents, recordings and other things may be lost or destroyed. Witnesses may die. The fact that the tribunal of fact is called upon to determine issues of fact upon less than all of the material which could relevantly bear upon the matter does not make the trial unfair.
 The respondents submit that in the event error is established their application should be remitted to the Supreme Court of Tasmania given what is described as “the complexity of the factual matters”. This submission should be rejected. The exercise of the primary judge’s discretion has been shown to have miscarried. It is open to this Court to reach its own decision in substitution for that of the primary judge in circumstances where, as here, the materials are before it.
 It is well established that the circumstances in which proceedings may be found to be an abuse of process are not susceptible of exhaustive definition. It is not necessary to consider whether there may be circumstances in which the loss of admissible evidence occasions injustice of a character that would make the continuation of proceedings on indictment an abuse of the process of the court. This is not such a case. The content of the Monitor List and the recording made by the FDR is unknown. In these circumstances it is not correct to characterise their loss as occasioning prejudice to the respondents. The lost evidence serves neither to undermine nor to support the Crown case. It is to be observed that if the Crown is unable to exclude the hypothesis, that the runway lighting was illuminated as the aircraft moved along it and that it ceased operating coincidentally at the time of take-off, it would fail to establish an element of the principal and the alternative offence.
 There is no feature of the delay that justifies taking the extreme step of permanently staying proceedings on the indictment. It has not been established that any prejudice arising by reason of the delay cannot be addressed by direction.
This is interesting, because the High Court didn’t think the loss of potentially exculpatory evidence warranted a stay. (And, it did note the evidence might have been incuplatory.)
I know of two authorities that might have suggested a different result.
In Boyce v Nunn (1997) 138 FLR 475;  NTSC 66, the Supreme Court of the Northern Territory allowed an appeal against an unsafe conviction. The accused was remanded in custody, so couldn’t interview a particular witness. The investigating police didn’t interview the witness, who might have provided exculpatory evidence.
In Rukavina v Police  SASC 247, the Supreme Court of South Australia allowed an appeal against conviction because exhibits weren’t retained for production at the original prosecution. That meant it was impossible to determine ownership of allegedly stolen property, and so the conviction was unsafe.
(Despite these two cases, there’s no general rule in Australia that a complete investigation is a necessary element of a trial or fair hearing: Penny v The Queen (1998) 155 ALR 605;  HCA 51.)
Neither case was cited in Edwards. But, though the two cases deal with a similar theme to Edwards, the precise point of law was subtly different. Edwards considered a permanent stay based on the absence of relevant evidence. Boyce v Nunn and Rukavina dealt with quashing unsafe convictions based on the absence of relevant evidence.
The High Court noted it wasn’t possible to tell if the missing evidence helped or hurt either party. And that meant its unavailability didn’t equate to prejudice. So it didn’t warrant such a drastic step as stopping the prosecution.
But the High Court did note the trouble the prosecution would have negating reasonable hypotheses consistent with innocence, because it didn’t have the missing evidence. That sounds like a pretty clear hint about what the High Court thought would happen when the charges were determined.
And presumably, if the charges did succeed, the airline pilots would then have a good chance of them being quashed on appeal, relying on the principles in Boyce v Nunn and Rukavina.
Moral of the story? Prosecuting agencies need to gather all evidence early, and keep it until charges are finalised. Hardly a novel idea, but still a valid observation.