You are in the SuddenTeams™ Expert System.
Every group creates rules, but usually this happens naturally without discussion and the rules remain unwritten. Unwritten rules are a leading cause of team conflicts and reduce the willingness of team members to communicate or cooperate. Each person assumes the other "knows better" when in fact the other doesn't know the rule he or she is supposedly breaking or sees it differently. Plus, new team members don't know the unwritten rules and thus are guaranteed to break them. The lack of clearly stated rules allows damaging behaviors to continue, as people following their own agendas can use the excuse, "Nobody told me I couldn't do that."
Fortunately, it is easy to create a set of written team rules: