There is an old adage among lawyers that says, "If you have the facts on your side, pound the facts; if you have the law on your side, pound the law; if you have neither the facts nor the law, pound the table."
Laws Of Conversation: How To Argue Like A LawyerIdentify The Issue And Don't Deviate From It. Recognise the main point of discussion and stick with it. ... Leave Emotion At The Door! Emotion will never win an argument. ... Be Wary Of Shifting Dialogues.
Oral arguments are spoken presentations to a judge or appellate court by a lawyer (or parties when representing themselves) of the legal reasons why they should prevail.
Good lawyers win arguments not by muddying the waters, but by sticking to one or two key issues and refusing to deviate from them. Arguments are not the place to blurt out hypotheticals and half-baked ideas. Avoid the natural urge to bring up unrelated matters when you feel like you're losing.