R v Haydon 2026
H, lived with his mother in Bedfordshire and had an interest in chemicals and explosives. He had converted a room on the first floor into a makeshift laboratory for storing chemicals and conducting experiments. H suffered from Attention Deficit Hyperactivity Disorder (ADHD) which manifested in an obsessive fixation with explosives.
On 10 April 2023, an explosion occurred in H's makeshift laboratory, causing serious injuries to him including blast injuries to his hands and chest requiring partial amputation of some fingers. The explosion was powerful enough to smash double-glazed windows and was heard by neighbours as a "thudding boom" that shook the adjoining wall of the semi-detached house. H told medical staff he had used acetone and hydrogen peroxide to cause an explosion.
Police and Explosive Ordnance Disposal teams secured the property, finding various chemicals, laboratory equipment, handwritten notes, and electronic devices. Chemical analysis identified triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), both sensitive primary high explosive substances, as well as other explosive materials. H's laptop contained numerous files with instructions for making explosives, and records showed he had purchased various chemicals online, including potassium permanganate, aluminium powder, ignitable fuses, sodium hypochlorite, and acetone. An SD card contained photographs and videos of H conducting explosive experiments, including detonating 10 grams of TATP inside a tree stump.
H was charged with one count of an offence contrary to section 2 of the Explosive Substances Act 1883.
At trial, H admitted causing an explosion but denied it was unlawful or malicious, claiming it was an accident and disputing that the level of explosives used would endanger life or cause serious injury to property. H was convicted following a 10-day trial at the Central Criminal Court and sentenced to an extended determinate sentence of 8 years and 6 months, comprising a custodial term of 4 years 6 months with an extension period of 4 years.
H appealed to the Court of Appeal on three grounds:
(1) The judge misdirected the jury on the meaning of "likely" in section 2;
(2) The judge wrongly admitted certain prejudicial evidence; and
(3) The judge misdirected the jury on the mental element of the offence.
H argued that the judge misdirected the jury on the meaning of "likely" in section 2 of the 1883 Act, contending that it should mean "more likely than not" rather than "could well happen," which sets a lower threshold. H submitted that case law supports the proposition that the natural and ordinary meaning of "likely" is a greater than 50 per cent chance, particularly when it imposes criminal liability.
It was also claimed that the judge erred in admitting photographs of devices and diagrams, arguing this evidence was unfairly prejudicial and should have been excluded under section 78 of the Police and Criminal Evidence Act 1984. Further more H contended that he was "a foolish and chaotic amateur" and the explosion was merely an accident.
On the mental element of the offence, H argued that the prosecution was required to prove that he intended to cause or was reckless as to causing an explosion of a particular magnitude likely to endanger life or cause serious injury to property.
Held
Appeal dismissed.
The Court of Appeal (Criminal Division) dismissed the appeal against conviction.
On ground 1, the Court held that the trial judge correctly directed the jury that "likely" in section 2 of the Explosive Substances Act 1883 means "could well happen" rather than "more likely than not". Parliament cannot have been using "likely" in the sense of "more likely than not" as this would leave outside the scope cases where an explosion could well endanger life or seriously injure property but falls short of being more likely than not. The Court reasoned that the purpose of section 2 is to protect the public from serious harm, with consideration given to the inherent dangerousness and unpredictability of explosive substances and the potential risk they pose to life and property. The Court agreed with the reasoning in R v Whitehouse that when the consequences of a risk materialising include great loss of life and damage, "likely" should be construed as meaning "a real risk, a risk that should not be ignored" rather than “more likely than not.” Drawing the line at "more likely than not" would introduce an arbitrary distinction between likelihoods and would fail to give sufficient weight to the underlying purpose of the Act, its policy intent, and the value of human life and property interests.
On ground 2, the Court found that the judge was correct to admit the evidence regarding explosive devices and diagrams, as it was relevant to show H's level of expertise and knowledge, which was relevant to whether his actions were accidental, unlawful, or malicious. The Court noted that the evidence was not presented to suggest any plan to harm others, which was made clear to the jury in summing up.
Finally, on ground 3 the Court determined that the mental element for a section 2 offence is confined to an intention to cause an explosion or foresight that an explosion might be caused, without any requirement to prove foresight of the degree of resulting harm. The Court determined there is no requirement to prove that an individual intended or foresaw an explosion of a degree which was likely to endanger life or cause serious injury to property, as this is a separate and objective question for the jury to decide. They also distinguished between the language of section 2 of the 1883 Act and section 1(2)(b) of the Aviation and Maritime Security Act 1990, concluding that the requirement of "malice" in section 2 means that nothing more needs to be proved than intention or recklessness as to causing an explosion.
Reproduced with permission of Reed Elsevier (UK) Limited, trading as LexisNexis.
View the full case document here, with links to related legislation and similar cases.