Stare decisis (“to stand by things decided”) sounds like a dry Latin phrase until the Supreme Court changes course in a way that affects constitutional rights, voting rules, criminal procedure, business regulation, privacy, speech, or the structure of government. Then the doctrine becomes something much larger than a law school definition. It becomes a question about institutional trust.

Stare decisis means courts generally stand by what has already been decided. Put simply, they don’t change “settled law” willy-nilly, on a whim, under political pressure, or in response to prevailing popular/public opinion or feelings.

It also does not mean every old case remains untouchable. It does not mean a wrong decision must remain law forever. It means the legal system has memory. Judges do not write on a blank slate every time a case reaches the courthouse. Prior decisions matter because people, legislatures, lawyers, businesses, prosecutors, defendants, courts, and public officials build their conduct around settled law.