And as what's his name said: The Law is a ass

Or even an ass to be pernickety, Faldage.
'Twere Dickens in Oliver Twist.

Actually would USns have any means of distinguishing between "donkey" (correct interpretation) and "arse" (incorrect, but equally apt) in a statement such as the one above? And would this be why you used an "a" rather than "an", thus specifying donkey? From a position of ignorance this does seem an eensy bit plausible...