The phrase ‘Fruit of the Poisonous Tree’ is a set word in Anglo-American common law. It stands in the context of illegal investigations, searches and seizures and the problem of whether ‘neutral’ information based on illegally gathered evidence can be acceptable in court proceedings. The relative amount of the metaphor is clear: If the foundation of the evidence (the tree) is tainted, then anything deriving from it (the fruit) bears the same flaw. In 1920 the U.S. Supreme Courte in the case of Lumber Co. v. U.S it was held that if during an illegal search investigators find a key to a post office box containing a crucial document which might prove the defendant’s guilt, this document will – as a rule – not be admissible as evidence in court proceedings since it is just one product of the unlawful search. To stick to the metaphor: the document is the fruit of the poisonous tree.