R v Dytham  QB 722 is a landmark case in English criminal law that dealt with the duty of a police officer to intervene in a criminal act. In this case, a police officer named Dytham was convicted of the common law offence of misconduct in public office for failing to intervene in an incident where a man was beaten to death outside a nightclub.
The incident took place when Dytham was off duty. Despite being aware of the incident, Dytham took no action to prevent the attack or to apprehend those responsible. He did not report the incident because he did not want to stay beyond the end of his shift.
At trial, Dytham argued that the offence of misconduct in public office required malfeasance, or at least misfeasance, and did not extend to nonfeasance. In other words, he argued that the offence could not be committed by an omission as it specifically requires misconduct. However, the court rejected this argument, stating that a police officer has a duty to intervene in criminal acts, whether on or off duty, and that Dytham had breached this duty by failing to take any action.
The case established the principle that police officers have a duty of care to all of society. It also clarified that the offence of misconduct in public office can be committed by an omission.
You can learn more about this topic and other case law with our Criminal Law notes.