Can an appeal court substitute a manslaughter verdict?

The question in one line.

When an appeal court quashes a murder conviction, does it have the power to substitute a lesser verdict of guilty of manslaughter, or is it confined to acquitting the accused or ordering a new trial? The High Court of Australia is now considering that question on an appeal from the ACT Court of Appeal. The answer will shape how a homicide appeal can end, and it will settle the reach of the appeal court's power to change a jury's verdict rather than send the case back.

Can a murder charge be downgraded to manslaughter?

Yes, and it happens in two very different places. The first is at trial. Manslaughter is the classic alternative verdict to murder. Where manslaughter is open on the evidence, the trial judge must leave it to the jury, whatever the attitude of the Crown or the accused. The jury can then return manslaughter instead of murder. It reaches that result if it is not satisfied of the murderous mental element but is satisfied that the accused caused the death by an unlawful and dangerous act or by criminal negligence.

The second place is on appeal, and it works in a different way. A convicted person appeals the murder verdict. If the appeal court decides the murder verdict cannot stand, one option open to it, in some cases, is to enter a verdict of guilty of manslaughter in its place. That is a substituted verdict. It is the appeal court, not a jury, that records the manslaughter conviction. The power to do so is the subject of the current High Court appeal.

What power does an appeal court have to substitute a verdict?

The power is statutory. In the ACT it sits in section 37O of the Supreme Court Act 1933 (ACT), which sets out the orders the Court of Appeal can make on a conviction appeal. In NSW the equivalent is section 7(2) of the Criminal Appeal Act 1912 (NSW).

The NSW section is the older and more familiar model. It allows the Court of Criminal Appeal to substitute a verdict of guilty of another offence where two conditions are met. The jury could, on the indictment, have found the accused guilty of that other offence. And it must appear to the court that the jury, by its verdict, must have been satisfied of facts which prove the accused guilty of that other offence. The court can then pass a sentence for the substituted offence, but not one more severe than the sentence passed at trial.

Those conditions matter. The power is not a general licence for the appeal court to pick the verdict it prefers. It rests on what the jury must be taken to have decided. Where the jury convicted of murder, the question is whether the jury's verdict shows it was satisfied of the facts that make out manslaughter as well. The dispute in the ACT case is whether section 37O(1)(d) of the Territory Act carries the same substitution power, or whether its words confine the Court of Appeal to other orders.

What did the High Court decide in Baden-Clay?

The Queen v Baden-Clay [2016] HCA 35 is the leading modern authority. A Queensland jury convicted the respondent of murder. The Queensland Court of Appeal found the murder verdict unreasonable and substituted a verdict of manslaughter. It did so on a hypothesis raised for the first time on appeal: that there had been a physical confrontation in which a fatal blow was struck without the intent needed for murder.

The High Court allowed the Crown appeal and restored the murder conviction. It held, unanimously, that the hypothesis relied on by the Court of Appeal was not open on the evidence. The respondent's own account at trial left no room for it. The lesson runs two ways. An appeal court that reviews a jury verdict must respect the jury's function and cannot set the verdict aside on a theory the evidence does not support. And an appeal court cannot substitute a lesser verdict on a factual basis the jury never considered and the evidence never raised. Baden-Clay is the reason the substitution power is read with care.

Is it worse to be charged with murder or manslaughter?

Murder is the more serious charge, and the gap is large. In the ACT, murder under section 12 of the Crimes Act 1900 (ACT) carries a maximum of life imprisonment. Manslaughter under section 15 carries a maximum of 20 years, rising to 28 years for an aggravated offence. In NSW, murder carries life under section 19A of the Crimes Act 1900 (NSW), and manslaughter carries a maximum of 25 years under section 24.

The line between them is the mental element, not the fact of a death. Murder requires an intent to kill or to cause really serious injury, or reckless indifference to human life, or a killing in the course of certain other conduct. Manslaughter covers a death caused by an unlawful and dangerous act, or by criminal negligence, without that murderous state of mind. Two accused can cause a death in similar physical circumstances and face very different charges because of what the Crown can prove about intent. That is why the choice between the two verdicts, at trial and on appeal, decides so much.

What is happening in the High Court appeal?

The following is a fair report of steps that appear on the public record of the courts. At trial in the ACT, a jury returned a verdict of guilty of murder. On appeal, the ACT Court of Appeal set aside that verdict in O'Connell v DPP [2025] ACTCA 20. After further submissions on whether another verdict should be entered, the Court of Appeal by majority substituted a verdict of guilty of manslaughter in O'Connell v DPP (No 4) [2025] ACTCA 41, delivered on 29 September 2025. The person was later sentenced for manslaughter.

The matter is now before the High Court of Australia as Director of Public Prosecutions v O'Connell, case number C2/2026. The central question is whether section 37O(1)(d) of the Supreme Court Act 1933 (ACT) permits the Court of Appeal to enter a substituted verdict at all, and if so, on what conditions. The High Court heard argument in May 2026. Its decision has not been delivered. Nothing in this article should be read as a view on the outcome, or as a statement of fact about any person's guilt; the appeal is undetermined and the ordinary rules about matters before a court apply.

What happens if the substitution power does not apply?

If an appeal court sets aside a murder verdict and cannot substitute manslaughter, it is left with two orders. It can enter a verdict of acquittal, which ends the prosecution. Or it can order a new trial, which sends the case back for a fresh jury to decide, on the charges the Crown chooses to press.

The stakes in that choice are real for an accused. A substituted manslaughter verdict fixes a conviction and a sentence without a further trial. An acquittal is a complete end. A new trial reopens the whole case, with the cost, delay, and risk that a second jury brings. The scope of the substitution power decides which of these paths is available, and that is why the High Court's answer will be read closely by every homicide practitioner in the ACT and beyond.

Why this matters for a person facing a homicide charge.

The alternative verdict is not an afterthought. It is run at trial. Defence often asks the judge to leave manslaughter to the jury, so that a jury with a doubt about intent is not forced to choose between murder and a full acquittal. Whether manslaughter is left, and how it is left, can decide the case. The same fault line then runs into any appeal.

On appeal, the ground that the murder verdict is unreasonable is one of the hardest to run, because the appeal court gives real weight to the jury's advantage in seeing the witnesses. Baden-Clay shows how far that respect for the jury extends. Where the ground succeeds, the next fight is over the order: substitution, acquittal, or retrial. The pending High Court decision goes to that second fight. For anyone charged with murder in the ACT, the reasoning at both stages, the trial direction and the appeal order, is worth understanding early. Our related note on an unfair summing-up and a new trial covers the retrial path, and our explainer on murder and manslaughter offences sets out the elements in full. On sentence appeals and the re-exercise of discretion, see our note on Kentwell and manifest excess.

Frequently asked.

Can a murder charge be downgraded to manslaughter?

Yes, in two ways. At trial the judge can leave manslaughter to the jury as an alternative verdict where it is open on the evidence, and the jury can convict of manslaughter instead of murder. On appeal an appeal court can in some cases substitute a verdict of guilty of manslaughter after setting aside a murder verdict, but only where the statutory conditions are met and the jury's findings support the lesser offence.

Is it worse to be charged with murder or manslaughter?

Murder is the more serious charge. In the ACT murder carries a maximum of life imprisonment under section 12 of the Crimes Act 1900 (ACT). Manslaughter carries a maximum of 20 years under section 15, or 28 years for an aggravated offence. In NSW murder carries life under section 19A and manslaughter carries 25 years under section 24. The difference is the mental element, not the fact of a death.

What is the average sentence for murder in Australia?

There is no single average. Murder carries a maximum of life imprisonment across Australian jurisdictions. In NSW there is a standard non-parole period of 20 years for murder, which guides but does not fix the sentence. Head sentences and non-parole periods vary widely with the facts, the offender, and the case. A murder sentence is set on its own facts.

What happens when a jury cannot agree on a verdict?

If a jury cannot reach a verdict it is a hung jury and is discharged without a verdict. The prosecution then decides whether to seek a retrial before a fresh jury. A hung jury is not an acquittal and it is not a conviction. It is separate from an appeal, which challenges a verdict that has already been returned.

Can a manslaughter verdict be appealed?

Yes. A person convicted of manslaughter can appeal the conviction, the sentence, or both. Where an appeal court has substituted a manslaughter verdict for a murder verdict, that substitution can itself be challenged, including in the High Court, on the question of whether the appeal court had the power to enter the substituted verdict.

To speak to a criminal defence lawyer, call Aaron Kernaghan on 0421 717 019.

This article is written by Aaron Kernaghan, criminal defence lawyer at Good Legal Lawyers, as at 28 July 2026. It refers to DPP v O'Connell, a matter currently before the High Court of Australia. What is said about that matter is a fair and accurate report of steps on the public record of the courts. The appeal is undetermined; no view is expressed on its outcome, and nothing here should be read as a statement of fact about any person's guilt. Any person charged is presumed innocent. This article is general commentary and reflects the personal opinion of the author only. It is not legal advice, it is not a substitute for advice on your own matter, and it does not purport to be accurate or complete. For advice on a specific matter, contact Aaron Kernaghan on 0421 717 019 or contact the firm.

More criminal-law commentary by Aaron Kernaghan.

← Back to all news