If you've ever had a drink in your life (or used mouthwash) then there is never a point at which its zero. It's one of those things where it approaches zero without ever getting there. Its called an asymptote in geometry. It does of course get to a level where it is so small that it becomes...
I'd be interested to know how many of the 'holier than thou' posters on this thread have got into their car feeling a bit tired.
I'd advocate a zero tolerance policy. If you are more than zero percent tired when you get behind the wheel, you should be jailed in solitary confinement for 30...
No company would consider marketing such a thing due to the consequences of inaccurate results leading to conviction or worse - accidents, even death. You can get those rubbish French ones that you were bizarrely required to carry by law when driving in France a while back, but they only give a...