One might as well be hanged for a sheep as a lamb
Q From Jo Ward: Have you heard of the saying you might as well be tried for a lamb rather than a sheep or something like that?
A Something like is right. The standard form is one might as well be hanged for a sheep as a lamb, though you sometimes come across it as one might as well be hanged for a goat as a lamb. Strictly, it’s a justification or excuse for going on to commit some greater offence once one has perpetrated a minor one. These days it often suggests that once one has become involved in some affair or incident (not necessarily illegal), one may as well commit oneself entirely.
This example is from Sons and Lovers by D H Lawrence, of 1913: “It seemed as if she did not like being discovered in her home circumstances... But she might as well be hung for a sheep as for a lamb. She invited him out of the mausoleum of a parlour into the kitchen.”
The origin lies in the brutal history of English law. At one time, a great many crimes automatically attracted the death penalty: you could be hanged, for example, for stealing goods worth more than a shilling. Sheep stealing was among these capital crimes. So if you were going to steal a sheep, you might as well take a full-grown one rather than a lamb, because the penalty was going to be the same either way.
Since the law was reformed in the 1820s to end the death penalty for the crime, the proverb must be older; in fact the earliest example known is from John Ray’s English Proverbs of 1678: “As good be hang’d for an old sheep as a young lamb”.