E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
An enlightened, independent jury. The expression has its birth in certain trials held in Ireland in 1635 upon the right of the king to the counties of Ireland. Leitrim, Roscommon, Sligo and Mayo, gave judgment in favour of the Crown, but Galway opposed it; whereupon the sheriff was fined £1,000, and each of the jurors £4,000.