"One witness is not enough to convict anyone accused of any crime or offence they may have committed. A matter must be established by the testimony of two or three witnesses." (Deuteronomy 19:15)
When Israel enters the land, three cities of refuge are to be set aside; if the land is enlarged, three more are to be added. Roads must be built to them. The purpose is that someone who kills another person accidentally may flee there and live, not being caught by an avenger of blood when the killing was unintentional. The example given: two men in the forest chopping wood, and the axe head flies off and strikes the other man. He is to flee to the city of refuge. But the malicious neighbour who kills with intent and then flees to the city of refuge is to be handed over to the avenger.
One witness is not enough to convict anyone accused of any crime or offence they may have committed. A matter must be established by the testimony of two or three witnesses. If a malicious witness comes forward, the judges must investigate thoroughly; if they find the witness has lied, do to them what they planned to do to their brother. Show no pity: life for life, eye for eye, tooth for tooth. The Catechism draws from the two-witness requirement the principle of procedural justice: no person may be condemned on the basis of a single unverified accusation, and the false accuser is subject to the very punishment they sought to impose (CCC 2477).
Brothers and sisters, one witness is not enough. The principle protects every person from the malicious accusation that cannot be verified. It applies in courtrooms and in parish meetings and in family conversations. Do not convict a person on one voice alone. Investigate. The standard of two or three witnesses protects the innocent and exposes the malicious.
Lord God, you built protections for the accused into your covenant law: cities of refuge for the accidental killer, multiple witnesses for any conviction. Give your Church communities of genuine justice, slow to accuse and thorough in their investigation. Through Christ our Lord. Amen.