There are some federal rules governing work/rest. They have fences. They include the fact that if somebody doesn't feel that he or she is rested and can operate, the person can obviously book rest at any time.
One thing that happened after the Railway Safety Act review was that the unions, government, and the railway industry got together to look at fatigue. Their recommendation was to identify better fatigue management plans and procedures, which were integrated into that rule. Everyone agreed with the approach, so we're expecting a higher standard for fatigue management under the rules for the future.