The 290th prohibition is that we are forbidden from punishing someone based on our estimation [without actual testimony], even if his guilt is virtually certain. An example of this is a person who was chasing after his enemy to kill him. The pursued escaped into a house and the pursuer entered the house after him. We enter the house after them and find the victim lying murdered, with the pursuer standing over him holding a knife, with both covered with blood. The Sanhedrin may not inflict the death penalty1 on this pursuer since there were no witnesses who actually saw the murder.

The Torah of Truth (Toras Emess) comes to prohibit his execution with G‑d's statement2 (exalted be He), "Do not kill a person who has not been proven guilty."

Our Sages said in Mechilta:3 "If they saw him chasing after another to kill him and they warned him, saying, 'He is a Jew, a son of the Covenant! If you kill him you will be executed!' If the two went out of sight and they found one murdered, with the sword in the murderer's hand dripping blood, one might think that he can be executed. The Torah therefore says, 'Do not kill a person who has not been proven guilty.' "

Do not question this law and think that it is unjust, for there are some possibilities that are extremely probable, others that are extremely unlikely, and others in between. The category of "possible" is very broad, and if the Torah allowed the High Court to punish when the offense was very probable and almost definite (similar to the above example), then they would carry out punishment in cases which were less and less probable, until people would be constantly4 executed based on flimsy estimation and the judges' imagination. G‑d (exalted be He), therefore "closed the door" to this possibility and forbid any punishment unless there are witnesses who are certain beyond a doubt that the event transpired and that there is no other possible explanation.

If we do not inflict punishment even when the offense is most probable, the worst that could happen is that someone who is really guilty will be found innocent. But if punishment was given based on estimation and circumstantial evidence,5 it is possible that someday an innocent person would be executed. And it is preferable and more proper6 that even a thousand guilty people be set free than to someday execute even one innocent person.

Similarly, if two witnesses testified that the person committed two capital offenses, but each one saw only one act and not the other, he cannot be executed. For example: One witness testified that he saw a person doing a melachah on Shabbos and warned him not to. Another witness testified that he saw the person worshipping idols and warned him not to. This person cannot be executed by stoning.7 Our Sages said,8 "If one witness testified that he worshipped the sun and the other testified that he worshipped the moon, one might think that they can joined together.9 The Torah therefore said, 'Do not kill a person who has not been proven guilty.'"