I have not been able to find the answer (yet!)..can anyone please tell me the origin of the duty of care? (not to injure someone else)
To prove the defendant had a duty, what is the authority generally used? Any actual HELP is appreciated, but please, if you have criticisms of my purpose to learn or anything else about me, they are better kept to yourself.

Do unto others as you would have them, in similar circumstances, do unto you.

It's just plain basic human rights. Duty of care has been around since the earliest recorded human civilization or you wouldn't really have much of an ordered society now would you?

It should be found in Tort law, further specified in a statute maybe depending on your location. Unspoken contracts. Duty of care. If you still cant find it then try drawing authority from inherent jurisdiction of the court.