Where is the justice or justification in the statement "we don't make the laws, we just enforce them"?

i find law enforcement agents use this statement (and seem to find solace in it) quite a bit when faced with a question regarding an "unjust law" or cases of an unjust judicial system. im trying to take a complicated issue and put it in a simplified question. i mean no direspect and humbly ask for honest answers from those who wish to participate.