My response:
"Attorney-in-fact" is a term of art, so to speak, of the legal profession. It is a "post" or a "trust", or an "agency" bestowed upon a person by another (the principle) to do for the principle in the principle's name and authority, as if the principle were doing the act themselves, and for themselves.
For example, an Attorney-in-Fact, by virtue of a Power of Attorney, will allow such Attorney-in-Fact to transact business with a bank (withdrawing funds) on behalf of the principle, or buying a car for the principle, and the principle is as liable for the business transaction as if the principle had personally done the business transaction.
In California, this is accomplished by a fully executed and notarized "Power of Attorney", signed and dated by both principle and agent. An "attorney-in-fact" is NOT an "Attorney at Law", and therefore, does not give the agent the right to practice law. Like I said, it is merely a term of art.
IAAL