Well, it truly depends on the situation. As a general answer though, in America, we go by "due process", which means that everyone is innocent until proven guilty. If a person is proven guilty, they are expected to pay for their crimes with their time, money or services. Which means that a person would spend time in jail, pay a fine or do community service.
That's a pretty wide open explanation though. I would say that most American's feel that fair justice is when reparations for a crime are equal to the crime. Meaning that if you commit a crime, you are expected to clean up your mess, pay for what you broke, give back to a family you victimized or to serve jail time in an equal amount to the crime you committed.
I know this is a confusing answer. Does it help? lol