Staying calm allows you to think logically and take decisions accordingly. Clarity of mind is extremely important while you are dealing with problems. If your mind is free and relaxed, your clarity on thoughts shall provide the solution to you. Staying calm allows you to discuss things rather than fights.
If you’re triggered, annoyed or stressed out, you’re more likely to talk faster or blurt out something you’ll eventually regret saying. Whether you mean it or not, it wasn’t supposed to come out. Which is why I try to stay calm whenever I’m any of those and I come out pretty soft.
Because if someone is angry during argument, that leades to actions that could hurt someone. What i mean is that you will act without thinking. For example, you might insult them, hit them, etc. Keeping calm is alway the best answer because you will think better and will have better responses. You might be able to even stop the arguement.
Supreme court's are the best examples of appellate courts where the final review of civil as well as criminal cases is organised. Even original jurisdiction is practiced in supreme court.