(Exodus 23:7) says: "And a clean one and a righteous one you shall not kill." The Mekhilta applies this to a specific judicial scenario involving imprecise testimony.
Suppose one witness testified that a person worshipped the sun, and another witness testified that the same person worshipped the moon. Both witnesses agree that the accused committed idolatry, but they disagree about which idol was worshipped. Can their testimonies be combined to convict?
One might think yes — both confirm that idolatry occurred. The specific object of worship seems like a minor detail. But the Mekhilta says no. "A righteous one you shall not kill" — the accused is "technically righteous" because the testimony against him is inconsistent. Two witnesses did not see the same act. Their accounts contradict on a material point.
In Jewish criminal law, witnesses must describe the same event. Seeing two different acts of idolatry does not constitute valid combined testimony for a single charge. Each witness saw something different. Their testimonies cannot be merged, and the accused must be acquitted.
The Torah calls this person "righteous" not because he is innocent — he may well be guilty — but because the legal system cannot convict him based on inconsistent evidence. The presumption of innocence protects even those who may actually be guilty, when the evidence fails to meet the Torah's exacting standards.