Judges' decisions roughly backing principality (4,3)
I believe the answer is:
case law
'judges' decisions roughly backing principality' is the definition.
I can't tell whether this defines the answer.
'roughly backing principality' is the wordplay.
'roughly' becomes 'ca' (abbreviation for circa).
'backing' says the letters should be written in reverse.
'principality' becomes 'wales' (Wales is an example).
'wales' written backwards gives 'selaw'.
'ca'+'selaw'='CASE-LAW'
Can you help me to learn more?
(Other definitions for case law that I've seen before include "Legal precedent" , "legal precedents" , "It depends on precedents" , "It is based on precedent" , "A lot of precedents" .)