I personally would not feel that it necessarily needs to be a specialist. Perhaps only in instances where there may be questions with regard to the competence or capacity of the individual would there be a need for more specific, specialized expertise.
Evidence of meeting #8 for Physician-Assisted Dying in the 42nd Parliament, 1st Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was patient.
A video is available from Parliament.