## Facts

- Sergeant Alexander Blackman, a Royal Marine, was convicted of murder for shooting a wounded insurgent in Afghanistan.
- The incident was recorded on Blackman's helmet camera, capturing incriminating statements made during the shooting.
- Blackman's conviction was initially upheld by a military court.

## Issues

1. Whether Blackman’s mental state at the time of the killing met the legal criteria for diminished responsibility.
2. Whether combat stress and adjustment disorder could constitute a significant mental impairment affecting criminal responsibility.
3. The application of civilian criminal law standards to actions taken in a combat environment.

## Decision

- The Court Martial Appeal Court allowed Blackman’s appeal, substituting the murder conviction with manslaughter on the basis of diminished responsibility.
- The court found that Blackman suffered from adjustment disorder, which significantly impaired his capacity to make rational decisions or control his actions at the time of the killing.
- The decision acknowledged the psychological impact of prolonged combat exposure on judgment and behaviour.

## Legal Principles

- Diminished responsibility, as reformed by the Coroners and Justice Act 2009, requires evidence of a mental impairment arising from a recognized medical condition that significantly impairs understanding, reasoning, or self-control.
- The existence of a causal link between mental impairment and the act of killing is necessary to establish diminished responsibility.
- Adjustment disorder resulting from extreme stress, such as prolonged combat service, may constitute a recognized medical condition sufficient for this defense.
- Psychiatric evidence plays an important role in demonstrating how combat environments can impair mental functioning relevant to criminal liability.

## Conclusion

The Court Martial Appeal Court in R v Blackman established that adjustment disorder due to combat stress can amount to diminished responsibility, reducing murder to manslaughter where mental impairment significantly affects decision-making and control. This case clarifies the role of psychiatric evidence and acknowledges the specific impact of military service–related mental health conditions in determining criminal responsibility.


R v Blackman [2017] EWCA Crim 190