from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
GOD AND MY COUNTRY. When a prisoner is arraigned, he is asked, How will you
be tried? he answers, "By God and my country." This practice arose when the
prisoner had the right to choose the mode of trial, namely, by ordeal or by
jury, and then he elected by God or by his country, that is, by jury. It is
probable that originally it was "By God or my country" for the question
asked supposes an option in the prisoner, and the answer is meant to assert
his innocence by declining neither sort of trial. 1 Chit. Cr. Law, 416;
Barr. on the Stat. 73, note.