Q&A: The Fruit of the Poisonous Tree According to Jewish Law
The Fruit of the Poisonous Tree According to Jewish Law
Question
Hello and blessings, Rabbi Michael,
I recently came across the doctrine of the fruit of the poisonous tree, and I tried to think about what the Sages and Jewish law would say about this issue (admissible evidence obtained illegally or by means of a halakhic transgression), but no sources came to mind. Could the Rabbi point me to passages related to this question? I would also be glad to hear the Rabbi’s opinion on this specific issue, morally and halakhically.
Thank you.
Answer
There is a consideration here of future prevention versus present punishment. Perhaps the right approach is to accept the evidence and punish the person who committed the transgression. That way you achieve both deterrence and justice.
From the standpoint of Jewish law, I am not familiar with any clear treatment of the matter, and certainly not a sweeping one. There are related cases, such as a forged document—someone who forged a deed in order to create evidence through a migo claim—in Bava Batra 33a, or Tosafot on Gittin 4a regarding a document forged in its very text, and Rabbi Akiva Eger’s note there. There are of course various kinds of evidence that are disqualified indirectly because of transgressions, such as the testimony of a wicked person, but there the disqualification is not of the evidence but of the person. And that is not true for every transgression.
There is also the risk that criminals will use the police to threaten one another. Some mafioso threatens so-and-so: commit such-and-such a crime for me, or else I’ll leak incriminating information about you to the police. From here and there I’ve gotten the impression that this is one of the criminals’ stronger tools. And not only to induce someone else to commit a crime, but also to thwart competition—they can leak information. The drawback in eliminating competition is that the criminal thinks it will advance him, so how is the police supposed to know whether it really is worthwhile to arrest the one they were tipped off about, or whether in fact this will increase crime because they arrested the enemy of his enemy. As people once said, Israel’s policy of bombing locations led to manipulative use of the IDF by rival factions. This is the fruit of the anonymous tree, and you don’t know whether it is poisonous. I’m not familiar with the subject, and I haven’t seen whether or how people deal with this problem, which seems trivial and general.