Plea Bargaining?

When it comes to plea bargaining, why is punishment-maximizing needed through plea bargaining in a just society.

There are a few reasons.

Many times, if prosecuters think there is one suspect who is more dangerous to society than some of his or her partners in crime, they'll cut a deal with the others. They offer up information (something they don't technically have to do without a plea bargain, because that would fall under the right to not incriminate themselves) because that information is used to try the real heavyweight criminal. In return, they get a lighter sentence.

Also, plea bargains are used to incarcerate a person without taking the chance with a jury. Let's say a defendant is working with a flimsy alibi and some very bad circumstancial evidence, they can choose to take a plea bargain to be incarcerated or otherwise punished for a less serious crime. So if they know that they stand a real chance of being found guilty of murder, they'll be open to a plea agreement to plead guilty to involuntary manslaughter or murder two, to avoid the chance of getting a murder one conviction at a jury trial. The state's incentive there is that a trial by jury is a huge financial drain, and an emotional one for the victim or victims. They get their conviction and the defendant is still punished, even if it's not as much as it would be with a guilty verdict for murder one, without having to further traumatize victims or go through a formal jury trial.

Occasionally, a prosecutor will be sympathetic to the defendant. For example, there have been times where a woman who was a battered wife killed her husband in his sleep or in an environment other than a fight or attack. Since he was not actually attacking at that moment, it can't be called self-defense. The prosecutor can decide, at his or her own discretion, to take into account the years of abuse the woman endured at the hands of the murder victim and charge her with a lesser crime. They have to prosecute, and technically it would be murder, but because they see it as a justifiable homicide, they can decide not to go for the maximum.

It's important to the justice system because to win a guilty verdict, there have to be evidence and witnesses. The people most likely to have seen the crime are people who are a bit shady themselves. The promise of a lighter sentence for the crimes they committed is a really effective tool to get them to allow the prosecution to use them to win a case for the more serious crime. If they didnt' do that, they'd have even more crowded jails, filled with the mediocre crimes, and many many violent criminals would walk because of a lack of evidence.

don't commit crimes and it is moot