Tainted Evidence Law and Legal Definition

Tainted evidence is, in a criminal trial, information which has been obtained by illegal means or has been traced through evidence acquired by illegal search and/or seizure. It is also referred to as "fruit of the poisonous tree" and is not admissible in court. Public trust in the criminal justice system outweighs the need to preserve criminal convictions resting on tainted evidence.

For example, drunk driving convictions have been sought to be overturned because officers failed to follow accepted scientific procedures in mixing and storing the water and alcohol solutions used to calibrate the breath-testing machines used by troopers.