In all of these cases, you have the "legal" world mixing with the "medical" world. Definitions, definitions, definitions.

Sane.

Of sound mind.

Of mental clarity.

Clear.

Rational.

Judgment.

Sensible.

Mindful.

Reasonable.

Conscious.

Any of these words could be used to legally describe the medical requirements of the patient before a decision for euthanasia or assisted suicide in the conscious state could be granted. They could also be applied when describing the person who has been given medical power of attorney for someone who is incapacitated and a question of euthanasia is being considered. Who makes the final decision? Who is to say that these conditions exist?

It's a minefield. It won't be resolved anytime soon.