‘There is no relationship between what you find in a living person and what you find in a dead person"

Post-mortem drug test errors increasing:

“A technique for inferring how much of a drug a patient has taken may be putting innocent people behind bars.

The problem seems to be that doctors are incorrectly applying the method to corpses, in a bid to establish how much of a drug a deceased person took, or was given, before their death. That error can result in vastly inflated readings…” —New Scientist