There is a bigger issue that hasn't been addressed. In one way, Toliet Duck is right that there are technically "rules" in place so that no one should ever fly fatigued, ever.
The reality is that there is an inherent flaw in scheduling practices that I think everyone agrees, are outdated, The problem is that you are then expecting an exhausted person to recognize that they are fatigued. The number one problem with fatigue is that, when you are fatigued, chances are you are too tired to recognize this fact and act responsibly. How many times has the conversation in the van ride to the hotel included a statement that both pilots were are exhausted and shouldn't have flown?
The rules we have now are outdated. "Real" carriers that have work rules that are more conservative than the FAR's realize this, why else would there be a need to negotiate more rest or more restrictive duty guidelines? Other carriers, most regionals, have the majority of their work rules based in regulation. Everyone recognizes that these rules are outdated, even the FAA, obviously.
Just because there is a rule does not mean that there is adequate protection against error. Rules are broken every day, knowingly or unknowingly. If this rule were not flawed, I don't think that the NTSB would have had it on the top 10 most wanted list for so long. If we can make things safer by providing more rest and shorter duty periods, why would anyone be opposed? We add additional levels of safety that are not required by regulation to all aspects of our operations, but companies balk at these rules for economic reasons and staffing considerations. The point is that this isn't acceptable. As it stands now, airlines, regionals especially, do not do anything to mitigate the risk of fatigue. If anything scheduling practices encourage it. Fatigue calls shouldn't be the issue, because that will happen with or without new rules. The real issue is that the industry as a whole does not want to raise the bar because it will cost them money. Greed is what perpetuates the 8 hour reduced rest overnight.