A person who is, God forbid, involved in certain kinds of sinful behavior is disqualified from serving as a witness. These Halachot are especially important in the context of a wedding, when valid witnesses are required both for the signing of the Ketuba contract, and to witness the act of Kiddushin (when the groom gives the bride an object of value for betrothal). Care must be taken when choosing the witnesses, as appointing invalid witnesses could invalidate the Kiddushin.
We list here several examples of people who are disqualified from serving as a witness:
1) A person who is suspected of having an illicit relationship. The man is disqualified from serving as a witness even though there are no witnesses to the offense, but rumors have spread about his involvement in a forbidden relationship.
2) The Bet Shemuel (Rav Shemuel Feivush, Poland, 17th century), in Siman 42, rules that a man who hugs and kisses women who are forbidden to him is also disqualified from serving as a witness, on the level of Torah law.
3) One who is "married" to a non-Jewish woman. Even though a Jew cannot be Halachically considered married to a gentile, a man who lives with a non-Jewish woman as husband and wife is disqualified from serving as a witness, on the level of Torah law. According to the Kenesset Hagedola (Rav Haim Banbenishti, Turkey, 1603-1673), one is disqualified if he has relations with a non-Jewish woman even if they do not live together as a married couple.
4) One who eats the cheese of non-Jews or drinks the wine of non-Jews is disqualified from serving as a witness.
5) One who lends or borrows money on interest may not serve as a witness. Since it is forbidden by Torah law to accept interest or to pay interest, both the lender and borrower are disqualified.
6) A person who raises his hand to strike his fellow is disqualified from serving as a witness by force of Rabbinic enactment, whereas somebody who actually strikes a fellow Jew is disqualified on the level of Torah law.
7) It goes without saying that a "Moser" (somebody who cooperates with non-Jewish authorities in their persecution of Jews) is disqualified from serving as a witness on the level of Torah law.
8) A heretic who does not accept the authority of the oral tradition – the Mishna, Talmud, etc. – is disqualified from serving as a witness on the level of Torah law.
In light of these guidelines, it is imperative to choose people of the highest caliber to serve as witnesses at a wedding. Witnesses should not be chosen simply because of their close relationship to the bride or groom, or to their families; they should be chosen based upon their level of Torah observance, to ensure that they are valid. Discretion is far more critical when it comes to the witnesses than with regard to the Berachot recited under the Hupa. A wedding ceremony is perfectly valid even if the Berachot are not recited at all, and the personal religious stature of the people who recite the Berachot will have no effect upon the legal validity of the marriage. But if the witnesses are unsuitable, they undermine the validity of the Kiddushin. It therefore cannot be emphasized enough how important it is to ensure to choose men of a high religious caliber to serve as witnesses.
