The chairperson of every meeting is responsible for setting the tone. One assumes that all of the meeting participants have participated in training and understand how they are supposed to behave. However, it can’t hurt to remind people at the beginning of the meeting. Here is my script.
“Before we approve the agenda, I would like to remind everyone here of our rules. Only one person can talk at a time, no one is permitted to interrupt another participant except for the chair. We are going to discuss the items on the agenda. We are not going to talk about each others’ personalities or intellects. Does anyone have any questions? Hearing none, I will assume we all understand the rules and will be following the rules. Thank you.”
Try that and see if you have more effective meetings.