I think it depends on what the "panel" would be deciding. Again, t hey are not assessing the persons disability but their terminal disease which is causing them unbearable pain and the wish to end their suffering
If a patient has asked for doctor assisted suicide the first order would be to clarify if they meet the criteria
Criteria of terminal illness. Best decided by physician expert in the particular disease.
Criteria of overwhelming pain. Best determined by pain specialist. Most of those are docs but i do know a nurse practicioner specialist. I dont know of anyone else ,as you need to be able to order meds
Criteria of mental competence and no coercion. Best determined by a pyschiatrist along with testimony from family and any other care givers involved in care. Can see nurses, aides, social workers, ministers adding to level of understanding.
Determination of alternatives, ie better pain care, nerve blocks, need to be considered
In my experience, a complex patient in hospital has a care team, a care plan, regular family meetings to look at outcomes, options. These documents, as well as notes from others would form a reliable assessment of patient.