Fruit of the poisonous tree is a legal metaphor in the United States used to describe evidence that is obtained illegally. The logic of the terminology is that if the source (the “tree”) of the evidence or evidence itself is tainted, then anything gained (the “fruit”) from it is tainted as well. It’s well established and provides a nifty vehicle that may be utilized by Manafort who can allege that the bases for his charges stem from FISA warrants secured through reliance on the phony baloney Russian dossier. Novel? You betcha. Plausible? Absolutely.