Thank you for the question.
I share the concern that attempting to codify a definition of either term will end up resulting in harm. There is no question that, with the advances of medical science, which conditions are grievous and which ones are irremediable will change over time. If an attempt were made to codify those definitions statutorily, over time they would become both over- and under-inclusive of the population that should be provided access to the principle in Carter.
My submission is that they should be left where they currently reside, which is in the discretion of the treating medical physicians under the applicable college guidelines.