Answer
Based on official Jordanian legal texts
Witnesses are a pillar of the validity of a marriage contract under Jordanian law. Article 8 of the Personal Status Law requires, for the contract's validity, the presence of two witnesses — two men, or a man and two women, of the Muslims where the spouses are Muslim — who are of full age, sound mind, hearing the offer and acceptance and understanding that marriage is intended.
The purpose of witnessing is to publicize the marriage, distinguish it from anything else, safeguard rights, and prevent denial. This connects to the documentation of the contract under Article 36, which requires consulting the judge or authorized officiant and conducting the contract in the presence of witnesses and registering it.
The absence of witnesses affects the contract's validity: Article 31 treats a marriage without witnesses, or with witnesses who lack the required qualities, as an irregular (fāsid) marriage, so witnessing is an indispensable condition.
Assessing whether the witnesses' qualities are met and the witnessing is valid remains within the Sharia Court's competence on the facts of each case.
This is a general explanation based on Jordanian Personal Status Law and does not replace advice from a qualified lawyer in a specific dispute.