1,773. Agents Who Are Not Valid Witnesses

Hilchos Geirushin 7:19

A blind person may not deliver a get from outside Israel because he can’t confirm that it was written and signed in his presence. Therefore, if it was written and signed in his presence while he could still see and he only later became blind, he may say in front of three witnesses that it was written and signed in his presence, and deliver the get. Similarly, if a woman delivers a get from outside Israel, she must say in front of three witnesses that it was written and signed in her presence. These statements are only made in front of two men when the agent can also serve as a witness. In such cases, he joins with the other two and the three of them collectively validate the get based on his words. This is because a witness may serve as a judge in rabbinic matters.

Hilchos Geirushin 7:20

If an agent should fall ill or otherwise be prevented from fulfilling his mission due to circumstances beyond his control, he should go to a beis din and tell them that the get was written and signed in his presence. The court may then assign another agent to the task. The second agent doesn’t say that the get was written and signed in his presence. Rather, he states that he is acting as an agent of the court, after which he delivers the get in front of witnesses.