A single court decision can quietly govern the country for generations. That is the power of precedent: the past deciding the present, one ruling at a time.
A precedent is a past court decision that guides how later, similar cases are decided. Under the principle of stare decisis, courts generally follow precedent, so that the law stays consistent and predictable rather than shifting case by case.
Precedents bind downward. A ruling by a higher court must be followed by the lower courts beneath it. The Supreme Court's decisions become the law of the land that every other court must apply.
Lawyers and judges work with precedent like a toolkit. A precedent can be followed, distinguished by arguing the new case is meaningfully different, or, rarely and dramatically, overruled when a court decides the earlier decision was simply wrong.
The most famous reversals are landmarks precisely because precedent is usually so durable. When the Supreme Court overturned the separate but equal precedent in Brown v. Board of Education, it changed the nation. Such moments are rare by design.
