A more thorough explanation:

The King's Great Sessions in Wales was a common-law court established in 1543 in Wales. It had the same jurisdiction as the English assizes, but it was bound to follow English law, not necessarily English case precedent. The court was also known as the Court of Great Sessions in Wales.

For example, the Court of Great Sessions in Wales operated alongside the English courts and had the same jurisdiction in Wales as the King's Bench and Common Pleas had in England. However, it was not required to follow English case precedent.

In 1830, the Great Sessions were abolished, and England and Wales became one unified jurisdiction with the addition of two extra circuits to the English assize system.