I've frequently heard it said that people with potential involvement in a hearing (possible parties/witnesses/judges) about an incident should refrain from chatter about that incident prior to the hearing.
This seems intuitive, but I'm wondering: Is this guidance documented anywhere? (Is it correct?)
Relatedly, how much is it appropriate for a party to discuss potential testimony with a witness before calling the witness? Is it okay to dig deep into the details of what a witness saw and what they would say in response to various questions, before calling them?