A few points to address:
All very good but please tell me why someone who has never had a drink in their life should be jailed for the small amounts of alcohol that the body produces during the digestion of food.
That never happens to people in normal health. As I've repeatedly explained, endogenous alcohol levels are so low—100 to 1000 times lower than levels reached by drinking alcohol—that they are hard to even measure. They do not put anyone over legal limits.
In cases where endogenous alcohol levels are high enough to look like levels achieved by drinking, there's always some sort of significant abnormality or pathology involved, such as resections of the GI tract or pH abnormalities of the gut, combined with specific diets. Normal people do not produce measurable quantities of alcohol within their bodies.
And even if someone does produce significant alcohol internally, a BAC of 0.02 reached from intoxication with endogenous alcohol has exactly the same physiological effects as the same level achieved by drinking, So a pilot who is pulled aside for this level is unfit to fly, whether he got that way by drinking or through some abnormal condition that produced vast amounts of endogenous alcohol. Either way, unless he can bring that level down, his flying duty has ended. Above 0.04, he may be able to avoid certificate action if he can demonstrate that he did not achieve that level by drinking, but he's still grounded and medically unfit to fly.
Overall, endogenous alcohol is too rarely a cause of intoxication to be significant, even though numerous DUI lawyers hold this out as a sort of carrot to clients, implying that it can be successfully used as a defense (but it can't, unless it actually happened and that can be proved).
And where did substance abuse suddenly come from? Is blowing 0.23 now a sign of substance abuse? Am I right in suspecting, AnthonyGA, that you consider even a single glass substance abuse.
No, you're not right. How much you consume is irrelevant. What's relevant is how much alcohol you have in your blood when you engage in activities that can affect the safety of others or their property.
Substance abuse is abuse of a recreational or other drug in situations where it is inappropriate. Blowing 0.23 is fine when you're at home, or at a bar, or at a wedding, or whatever. But it's abuse if you blow it before entering the flight deck. Alcohol intoxication is unacceptable on the flight deck, and if you are intoxicated there, you're engaging in substance abuse.
It happens elsewhere.
Ever seen "Nurse Jackie"? A classic scenario of a health care professional on the edge... Who knows what the good doctor has in HIS bloodstream as he is trying to patch you up.
Two wrongs don't make a right. The fact that some health-care professionals may be intoxicated (and unfortunately it is a significant problem) doesn't mean that it's okay for pilots to be intoxicated, too. Instead, it's wrong for the doctors and nurses to be intoxicated, and they should be treated exactly as pilots are if they are found to be intoxicated while performing safety-related duties.
As it happens, pilots are in one of the most heavily regulated professions around, more regulated even than doctors and lawyers. But that doesn't mean that the standards for alcohol should be relaxed. Rather, they should be tightened for other professions affecting public safety.
There is indeed something "magic" about flying (in many respects). Every time a pilot is breathalysed, and even if he turns out to be completely innocent, it is "Drunk Pilot" in the Tabloids all round, and the usual bunch of sanctimonious prudes float to the surface here. How many other professions get that?
All of them, when a professional is caught intoxicated. It's just that most professions don't test for intoxication as diligently as the aviation industry—unfortunately. But a drunk train driver caught in that state gets a lot of press, too, if an accident occurs or if he is caught under circumstances that catch public attention.
In any case, talking about a drunk pilot in the tabloids is no big deal, provided that cooler heads prevail. If he really is drunk, it's time for a career change, and if he's not, he can simply continue flying. His fifteen minutes of fame will be over very quickly, and then he will be forgotten.
I wonder how many other people, if breathalysed at the start of their work day would be ridiculously past the limit airline pilots are required to meet, and 99.9% do, due to a few too many glasses of vino the night before.
In the United States, the great majority of those tested would be clean, with zero alcohol in their blood. And more than a few companies will fire employees who show up intoxicated, if they find out about it. Nearly half the U.S. population doesn't drink at all. However, the U.S. is unusually abstinent among developed countries. In France or the U.K., the number of people who don't drink at all is very low. Still, most of them would blow clean if tested upon arrival at work. Even in France, where about 16% of the population suffers from some degree of alcohol addiction, most people still arrive at work with no alcohol on board (although there are always a few who fairly reek of ethanol even at 7 AM—something that doesn't seem to bother French employers).