It’s on the lawful side (5)
I believe the answer is:
right
'side' is the definition.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for right that I've seen before include "The hand to the east when facing north" , "Correct; appropriate" , "Fitting; entitlement" , "Privy Councillors are so honourable" , "Fit" .)