Question:
Is a mother's sister's husband's brother considered a relative according to Torah law that would disqualify him to be a kosher witness?
Answer:
Hello,
Technically the uncle’s brother is not a real relative, nevertheless the custom is not to use him as a witness, similar to not using a “mechutan”, (two people who their children married each other) as a witness.
Best wishes
Sources:
חו"מ ס' ל"ג סע' ה', רמ"א אבה"ע ס' ק"ל סע' א'.
