Stare decisis is the idea that judgments previously issued should stand and that rules of law that are promulgated by the court should be carried forward without the court overturning them. And in criminal law, stare decisis is particularly important because it gives people notice of what the statute prescribes. The overturning of a previous decision can have the effect of expanding the effective scope of criminal law. One paradigmatic example of this is a number of state courts have abandoned the “year and a day” rule. So traditionally, for a homicide prosecution, the government must prove not just that the person caused the death in a blameworthy manner but that the victim died within a year and a day of when the fatal blow was struck. And so if a person shot a person on January 1st, 2000 and the person died on January 1st, 2005 of complications from the injury, a person would not have committed murder at common law because the injury became fatal more than a year and a day after the blow was struck. And a number of state courts have abrogated the year and a day rule and said it has no place in modern society where we can more definitively trace that the injury caused the death years after the blow was struck. But the effect of that is to have a kind of retroactive application that people who might not have been liable under the previous law, suddenly have become liable. It can also go the other way. You can have people that are convicted, say, of honest services fraud. And then the Supreme Court comes in and says, no, honest services fraud has to be much narrower than what we've previously assumed, and then you have a number of defendants who have final judgments against them, who were convicted under something that is no longer criminal. Laws are inherently vague at the margins, and it is only through judicial decisions that they become more concrete over time. And so, stare decisis is important in criminal law because judicial decisions help shape what are the vague margins of statutory criminal law. And people then go and rely not just on the law, but on the decisions explicating the law. And so a decision that upends the law can have quite significant effect. Even in a statutory criminal world, judicial decisions remain an important source of determining whether conduct is lawful or unlawful. And so stare decisis remains vitally important for keeping predictability in the law.