In the Role of the Judicial, how does the UK and US differ?

-In the UK: The Queen has the Royal Prerogative of Mercy, which isn't fully delegated to the PM. Furthermore, Justices are Appointed Independently to the Supreme Court via the Judicial Appointments Commission -In the US: The President has the Power of Pardon. The President can also Nominate Supreme Court Justices and Alter the Ideological Balance of the Courts