Google search results have shown inquiry about whether ‘tamper justice with mercy’ is correct. The simple answer is NO.
To ‘tamper’ is to make changes without permission, especially to damage, so it doesn’t correlate with ‘mercy’.
‘Temper’ means to make something less strong or extreme. Consequently, ‘temper justice with mercy’ is the correct expression and it is used to plead for lighter punishment for an offence.
Examples:
- We know he did it but if they don’t temper justice with mercy, he’d die in prison.
- Politicians always want the judiciary to temper justice with mercy when they are caught.