what are death certificates used for
The IRS may disagree, but the death certificate is arguably the most important legal document in existence. It's the only legal proof that someone has died. The State uses it to stop social security payments, pensions and other benefits. Families use it to settle their affairs. Since the reporting of death began in 1900, the information required on the death certificate has helped monitor and reflect how society is changing.
One purpose of the certificate is to review the cause of death to determine if foul-play occurred as it can rule out an accidental death or a murder going by the findings and ruling of the medical examiner.