There are three distinct legal jurisdictions in the United Kingdom: England and Wales, Northern Ireland and Scotland. Each has its own legal system, distinct history and origins. Wikipedia
The United Kingdom is a state made up of the historic countries of England, Wales and Scotland, as well as Northern Ireland. BBC
There are differences between the legal systems and the political systems which add to the complications.
Wales has a devolved assembly but shares a legal system with England.
Scotland has a parliament and a separate legal system.
The Northern Ireland Assembly is the devolved legislature for Northern Ireland but obviously isn't currently functioning. NI has separate legal jurisdiction within the United Kingdom established in 1921.
It isn't straight forward @Thereisasystem