A more thorough explanation:

Definition: By God and my country is a phrase that was historically used as a customary reply for a criminal defendant when asked at arraignment, “Culprit, how wilt thou be tried?” It means that the defendant is willing to be tried by a jury of their peers and is willing to swear to tell the truth.

• When asked how he would be tried, the defendant replied, "By God and my country."
• The phrase "by God and my country" is still used in some legal systems today.

These examples illustrate how the phrase "by God and my country" was used historically and how it is still used in some legal systems today. It shows that the defendant is willing to be tried by a jury of their peers and is willing to swear to tell the truth.