How come the rest of us don't get to use excuses like this? I wasn't intentionally drink driving, a barman with a grudge rubbed vodka into my legs....
Well, in all fairness that's not a fair comparison.
Alcohol is not absorbed into the system enough to make a difference in a test for alcohol, which is at a very high level (comparitively speaking).
Two things are at play here. Since the sixties, instrumentation for measuring levels of just about any substance have become ridiculously sensitive, and the level of certain substances may be set absurdly low for banning. Ways of introducing those low levels are so trivial it could happen to anyone... Just eating out at the wrong place will do it. Or contaminating snack food.
Having said that, I think he's guilty; lying under those circumstances is a given.
However, being "set up" is a real and almost unavoidable possibility.