An fMRI would be the most conclusive test in my opinion. Because that would be able to show which specific areas of the brain are still functioning, and from that, they could approximate her mental status, based on what they think those areas of the brains functions are... But then again, she couldn't have had one unless her "husband"
gave consent, to have the electrodes in her brain surgically removed. Which he would not do... Though i dont see what he stood to lose if they did.

I do agree that it was blatantly unconstitutional, but on the legal side, im pretty suprised that they would take some off handed comment about not wanting to live if hooked up to tubes, and that somhow translates into some kind of living will... Hearsay like that isn't usually legally binding...