Every MUN has to have rules about how itr conducts its meetings. These can be formal or very informal but they must be agreed to and abided by all participants. Having clearly defined written rules enables the participants to make reference to them whenever there is a disagreement about how to proceed.
Many International MUN conferences use the THIMUN Rules of Procedures or adaptations of the THIMUN Rules. This is because the THIMUN Rules have developed over a continuous period of more than 30 years and have been useful in facilitating debate and in enabling delegates to produce worthy resolutions.