Mishpatim: Rav Hirsch: Mitzvah 86 – Concept 555
“Distance yourself from a false word. Do not execute the innocent or the righteous, for I shall not exonerate the wicked.” (Exodus 23:7) The court must not execute anyone on circumstantial evidence. (Rambam, Hilchot Sanhedrin)
A judge who feels convinced that the case in which he has to give judgment is based on a fraud, but has no definite proof of it, may not give a verdict contrary to his conviction on the strength of the testimony of the witnesses, and quiet his conscience by saying that the responsibility for his judgment rests on the witnesses. In such a case the judge must withdraw from the case. (Rabbi Samson R. Hirsch)