Procedurally, criminal law and civil law are totally different systems. From ancient Rome to the present day, societies use a criminal/civil distinction. Seems to be something pretty close to a human universal. In criminal law, paradigmatically, someone gets accused of a crime, police come and arrest them, prosecutors indict them, and if the jury finds him guilty, he's sent to prison. He's punished. In civil law, someone sues, both sides lawyer up, they have a dispute, let's say in the courtroom, the jury doesn't find someone guilty, it finds someone liable, and the person who's found liable owes the other money damages. So what's the distinction all about? Well, philosophical as the question is, it comes up in cases- it comes up in cases because the US Constitution makes distinctions between the rights defendants have in the civil context and the rights defendants have in the criminal context. So, for example, Amendment Six says in all criminal prosecutions “the accused shall enjoy the right to a speedy and public trial.” Well, those rights only apply in, as the text says, in criminal prosecutions. Every once in a while, courts have to figure out whether we're on the criminal or civil side of the line. And the United States Supreme Court has developed legal doctrine in this respect and the basic rule is this: where there is punishment, there you have criminal law. Punishment is at the very heart of criminal law. When someone gets sued and found liable and owes money damages, they might not like the result, but they're not really being punished. The money is something they owe. Say, they breached a contract and they owe damages for that. But when someone gets accused of a crime and found guilty and sent to prison, that is punishment, that's moral condemnation, and it's hard treatment, and it's control by the state. Surprisingly, there is no concrete, clear definition of punishment in American law. The courts just haven't settled on a definition that everybody agrees to. But let me make a suggestion: Punishment is a sanction imposed by the state in virtue of the community's moral condemnation. That is, punishment is a condemnatory sanction. It's gotta have both pieces, there's gotta be the sanction element, the unwanted hard treatment, but since we have sanctions in other contexts, too, it's gotta have a second piece. The moral condemnation piece. It's the juxtaposition of moral condemnation and hard treatment by the state. That’s punishment. So here's the big picture: In every society, as in every family, there are disputes. One spouse thinks the other should help with the dishes more. One person thinks another has breached a contract with him. And civil law exists to peacefully resolve those disputes. But there's another kind of problem: the problem of wrongdoing. These are things like violent attacks on another, arson, sexual assault, treason against the state. These are the kinds of wrongdoing that are so wrongful and so dangerous that we as a society just can't live with them even if the offender pays damages. Societies everywhere respond to major wrongdoing with punishment. And that's what criminal law is all about. Criminal law is the piece of the legal system that deals with punishment for major wrongdoing. That's the heart of it.