are there laws govering medical power of attorney/advance directive/living wills

medical authority
does a physician have the right to decide when the when a living will should go into effect, and then put the living will into action

Primary Caregiver
The father of my 22 year old daughter is dying of cancer and is unable to make decisions himself. He has no living will or appointed any surrogate, or power of attorney. Who makes the decisions regarding his care, such as hospice?

living wills or lack thereof
a 56 yr old women on life support. very little brain function. no living will. what rights does her family have in allowing the ”plug to be pulled”? It would be her mom, a sister and a brother. There is no child nor husband. Patient would be appalled to live in this condition.

notarizing
does a lawyer need to sign a health care surrogate and/or a durable power of attorney