We didn't necessarily pick six months. That was just one of the time frames that was being discussed.
I think we need to remember that in the Carter decision some of the statements made included the words “vague”, “grievous”, “irremediable”, and those kinds of things. The justices were talking about a specific fact situation and referred back to this concern that somebody would take their life prematurely if they would not have assistance available to them at a later time when their suffering became intolerable and they were unable to end their lives themselves.
This implies that the patient has reached a point where they're nearing the end, and they're no longer able to take their own life. This is a key element in the Carter decision. We're talking about people who are not physically capable of taking their own lives, which implies a state of irreversible decline in capability. It implies that death is reasonably foreseeable.
I am not a lawyer, so I am by no means a legal expert. However, to my understanding, what is in this bill complies very closely with the Carter decision.