An autopsy is a routine procedure, usually conducted to determine a person's cause of death prior to issuing a death certificate. Toxicology tests, on the other hand, are usually ordered when someone is the victim of a crime, dies unexpectedly or dies for no obvious reason. The results of either test are officially recorded in a report and may even be used in a subsequent civil or criminal lawsuit.
TL;DR (Too Long; Didn't Read)
An autopsy is an external and internal examination of a deceased person's body to determine cause of death. A toxicology report is an analysis of the decedent's bodily fluids to determine whether that person had any poisons, drugs or alcohol in her system when she died.
Reports Help Explain Cause of Death
During an autopsy, the physician looks for evidence of disease, injury or other abnormality by investigating both the inside and outside of the body, including the brain, tissues and organs. Once complete, the doctor discloses his findings in an autopsy report, often listing the cause of death on the decedent's death certificate.
Toxicology tests can be conducted on living and deceased persons and go further by testing for the presence of prescription drugs, commonly abused substances like alcohol, cocaine or marijuana, or a particular poison in the body. The findings are disclosed in a toxicology report and indicate whether any drugs or poisons in the body led to the person's illness or death. For example, if the autopsy reveals damage to organs and tissue consistent with death by poisoning, a toxicology panel will confirm that cause of death by showing whether the decedent had poison in his system.
Autopsy and Toxicology Reports Used as Evidence
Autopsy and toxicology reports are routinely used as evidence in lawsuits and in criminal cases. For example, if a family is struck and killed by a drunk driver on their way back from Disneyland, the attorney prosecuting the drunk driver may use each family member's autopsy report to show that they died from injuries sustained in the car accident and not some other unrelated cause. The prosecutor also may use the defendant's toxicology report to show his blood alcohol level was over the legal limit at the time of the accident.
Other common uses for autopsy and toxicology reports include wrongful death and medical malpractice lawsuits. An autopsy will show that the victim died for a particular reason. For example, if a surgeon makes a bad choice and the victim bleeds out, the autopsy will reveal that the cause of death was blood loss, and it will also reveal the injury that resulted in the blood loss.