The coroner must hold an inquest where the death was:

• Unnatural or violent;
• Sudden and of unknown cause;
• In police custody or in prison.

Where the cause of death is unknown, the coroner may order a post mortem examination in order to determine if the death was violent. An inquest is unnecessary if the death is found to be non-violent.

If the death occurred in prison or in police custody, or if it falls under the Health and Safety at Work Act 1974, or in the execution of a police officer's duty, a coroner must summon a jury for an inquest as it affects public health and safety.

The coroner can also call a jury at his or her own discretion, wherever they feel appropriate.

In light of the Human Rights Act 1998, this discretion has been heavily litigated, meaning that juries are required now in a broader scope of situations than expressly required by statute.