An accurate device for telling you your level accurately would be helpful for knowing an individuals level before performing any function that has a limit. At the moment you have the bodies rate of removal coupled with total units consumed and the 8 hour rule, all of which are as good as useless.
The only sure way is to give up, but for everybody else ie normal everyday people who are drivers, train drivers, pilots, engineers, dispatchers etc the knowledge that you are safe to operate is vital.
It can't be that difficult to produce an approved handheld tester? Then this would not be happening.
Out of interest is a security staff member included in the legislation as their task is also an aviation safety issue?
D and F