Given, as has been pointed out, that the limit appears to have been set as low as can be measured, and furthermore that any impairment to judgement is quite probably less than suffered by a pilot at the end of a "legal" but long duty, or indeed suffering from a heavy cold, I find it difficult to justify shoving this individual in jail for 6 mths.
If he has been proven to be a habitual offender, that is quite another matter, but for the moment I feel less lonely perched on my soapbox than perhaps you should.