A Bicycle is a vehicle. Just as a horse is. Drunk in charge of a vehicle (on a public road) is apparently against the law. Falling off the bike (or horse) at the cops feet is sufficient evidence for breath testing/arrest...
Even walking drunk in a public place (not always on a road) is enough for a drunk and disorderly charge. Although some police use their descretion at such times ... and just lock them up for detox. (Some ... may take them home if the attitude test is passed)
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