Precedent (noun)

1. An earlier event or action that is regarded as an example or guide to be considered in subsequent similar circumstances.
2. A previous legal case or decision that serves as an authoritative rule or pattern in later similar or analogous cases.

Origin:

From middle english precedent, from old french precedent, from latin praecedentem, present participle of praecedere ("to go before"), from prae ("before") + cedere ("to g.o")

Examples:

1. This decision sets a dangerous precedent.
2. The court's ruling established a precedent for future cases.
3. His actions set a bad precedent for the company.
4. The court's ruling created a precedent that would be followed in future cases.
5. The precedent set by the Supreme Court's decision will have a lasting impact.