Does the law mandate such an appointment? Should it, and if so, under what circumstances?
The Rules of Professional Conduct prohibit representation of multiple clients when there is a potential conflict of interest, unless the client consents, which Terri could not do.
RULE 4-1.7 CONFLICT OF INTEREST; GENERAL RULE
(a) Representing Adverse Interests. A lawyer shall not represent a client if the representation of that client will be directly adverse to the interests of another client, unless:
(1) the lawyer reasonably believes the representation will not adversely affect the lawyer's responsibilities to and relationship with the other client; and
(2) each client consents after consultation.
(b) Duty to Avoid Limitation on Independent Professional Judgment. A lawyer shall not represent a client if the lawyer's exercise of independent professional judgment in the representation of that client may be materially limited by the lawyer's responsibilities to another client or to a third person or by the lawyer's own interest, unless:
(1) the lawyer reasonably believes the representation will not be adversely affected; and
(2) the client consents after consultation.
(c) Explanation to Clients. When representation of multiple clients in a single matter is undertaken, the consultation shall include explanation of the implications of the common representation and the advantages and risks involved.
To clarify the conflict of interest:
Michael said Terri wanted to die, and he hired a lawyer to get permission to kill her.
Terri's parents said Terri wanted to live, and they hired a lawyer in order to prevent Michael from killing her.
Who represented Terri? The GAL was appointed to make sure her rights were protected, and Florida law allowed, but did not require, the GAL to recommend that independent counsel be appointed for her. Please note that by "appointed" the law doesn't mean "paid for by the government." She had plenty of money for her own lawyer.