The fruit of the poisonous tree is a legal metaphor. It refers to evidence that was gathered after your civil rights were violated, but independently of the violation.nnUnder the metaphor, the unlawful search or seizure is the poisonous tree. Because the tree is poisoned by the violation of your rights, all subsequent evidence obtained – the fruit of the tree – is also tainted. Evidence tainted by the civil rights violation can be suppressed and excluded from the criminal trial.