If one is found not guilty of charges or found guilty and sentenced to some lesser degree of harshness than the guilty person might find 'just', that person might adjust their own morals to be more inline with that sentence.
In this sense law is to be seen as a codified extension of the sum of morals of the individuals that make up society. If we define propriety as the sum of all individuals' perspectives, we can understand that law is formalized propriety expressed through language.
This language is interpreted by the courts through the legal process.
The importance of the sum of all the individuals' perspectives on morality is that no person can truly enter another persons' shoes. Each persons' life experience is so complex, moment to moment, that no perspective could ever be said to be near the same.
Each persons view is so unique that we cannot properly weight one's perspective more moral than another individuals' perspective.
By considering the largest amount of person's viewpoints together we are able to get a least prejudice view. Propriety, as the aggregate (sum) of the individuals' views, is the ultimate objective (unbiased) viewpoint.
If law forgives you, so does propriety, and therefore so should you forgive yourself.
If law demands retribution, you should abide, but suffer no more so than asked or required (whether economically, physically, OR psychologically).
If law calls for rehabilitation, one can be assured that society admits at least partial blame for the guilty persons' circumstances.