Without any doubt whatsover "His guilt was proved beyond a shadow of a doubt." "After being the top scorer in the league, his ability as a football player was proved beyond a shadow of a doubt."

Without a shadow of a doubt = it is absolutely, without question, certain, it will definitely happen! "Yes dear, without a shadow of a doubt, i will make it to our dinner tonight." " Miss dad's birthday party? No way, without a shadow of a doubt, I will be there." "Do not call the repairman, I know how to fix it and i will. It's beyond a shadow of a doubt." It is often used because past history indicates the person might not actually arrive or make the " thing" happen.