From a different occupation, but when you are seriously tired / fatigued, all these very sensible but convoluted legal arguments are not being considered. Having the courage to say to authority that you are too tired to be continuing with your duties is a hugely stressful event in itself. Having the wherewithal to consider how a judge/jury may consider your approach to the problem is the least of your concerns! It's very simple. If a professional feels this way, then they need to go to the hotel / home, and talk about it 12 hours later. The only logic for getting a medical professional would be if there were a consideration of intoxication.