Cause, Mechanism, and Manner of Death: What's the Difference?

A death certificate answers more than one question. It says what caused the death, and it says under what circumstances the death happened. Those are different questions with different words. This article explains the three terms you may see.

What is the cause of death?

The disease or injury that set the events in motion. The Harris County Institute of Forensic Sciences describes it as a specific disease or injury. The ASCP’s Lab Medicine Blog gives an example: cardiac ischemia, meaning too little blood flow to the heart, can be due to atherosclerosis, spasm of an artery, or blood loss from an injury. Those are the causes. Ischemia is what each one did to the body.

What is the mechanism of death?

The body process by which the cause kills. Pathologist Alison Krywanczyk writes that the mechanism describes the biochemical and biophysical processes through which the cause has its deadly effect. An abnormal heart rhythm is an example.

Why is “cardiac arrest” not a cause?

Because it describes being dead, not why. The Harris County glossary says “cardiorespiratory arrest” is a description of being dead and not a cause. Krywanczyk makes the same point: everyone who dies is in cardiac arrest, so the certificate needs to say what caused it. A certificate that lists only a mechanism does not help families understand what happened or learn about their own medical risks. It also gives public health researchers no useful information.

What is the manner of death?

The circumstances of the death. There are usually five choices:

• Natural: death due solely or nearly entirely to disease or the aging process. If an injury, such as a fall, hastens a natural death, the manner is not natural.
• Accident: there is little or no evidence that an injury or poisoning was meant to cause harm.
• Suicide: an intentional, self-inflicted act meant to cause harm or death to oneself.
• Homicide: a death caused by another person. This is not the same as murder, and the Harris County glossary says intent to cause death is not required.
• Undetermined: used when the evidence for one manner is no more compelling than the evidence for another.

Can the same cause have different manners?

Yes. Forensic pathologist William Cox gives the example of a gunshot wound to the chest. The cause of death is the same in each case. The manner could be homicide, suicide, or accident, depending on the circumstances. He also notes that a driver who strikes a pedestrian through negligence could face a manslaughter charge, yet a medical examiner could still call the manner an accident, because the driver did not intend harm.

Who decides?

In many places, a medical examiner or coroner decides for deaths that are sudden, violent, or unexplained, and a physician certifies an expected death from illness. Laws differ by state. In Texas, for example, the Harris County glossary says state law requires the medical examiner to determine cause and manner in all deaths ruled accident, suicide, homicide, or undetermined. See Coroner vs. Medical Examiner.

What goes on the certificate besides the cause?

A chain of events, and other conditions that played a part. The ASTHO summary explains that a second section of the certificate is for other significant conditions that contributed to death. It also says “cardiac arrest due to multiorgan failure” is inaccurate because it hides the underlying disease. Krywanczyk says a common manner error is overlooking a fall-related injury in an older or frail person. The CDC offers a free online training on death certification.

Where can I learn more?

See Autopsy Explained, What Does Dying of Old Age Actually Mean?, and How a Doctor Pronounces Death.