Depends on how you mean this. I'm going to answer for America. If anyone wants to add other countries, great!
First, a doctor is a Covered Entity (CE) under HIPAA, the main US medical privacy law. He is allowed to transfer Protected Health Information (PHI) without the patient's approval under the following circumstances:
All this does not require any authorization from the patient, so there's nothing to sign.
So there's really no need for the doctor to sign on the patient's behalf, nor is there any legal grounds that would allow such.
Yes, a parent can legally sign a contract on behalf of a minor in most cases.
Yes, a spouse can legally sign documents on behalf of their partner if they have been given specific authorization or power of attorney to do so.
Yes, a wife can legally sign a check on behalf of her husband if she has been given the authority to do so, such as through a power of attorney or joint bank account.
Yes, a property manager can legally sign a lease on behalf of an owner if they have been given the authority to do so through a written agreement or power of attorney.
It is not illegal to transfer money on behalf of another person as long as you have their permission and are not involved in any illegal activities such as money laundering or fraud.
a parental guardian
Yes, a minor can legally own property, but they may need a legal guardian or trustee to manage it on their behalf until they reach the age of majority.
Yes, minors can legally own property, but they may need an adult to act as a guardian or trustee on their behalf until they reach the age of majority.
Generally, yes.
Someone who is legally authorized gives consent on the subject's behalf
when they have credible reason and proper documentation
Yes, having power of attorney can make you legally responsible for the actions and decisions made on behalf of the individual you are representing.