precedent

An earlier event, action, or decision that serves as a guide or justification for subsequent similar circumstances.

• unprecedented/ʌnˈprɛsɪdɛntɪd/(adj)史无前例的

• set a precedent
• legal precedent
• without precedent
• break with precedent
• historical precedent

1. 1.The court's ruling set a precedent that would shape privacy law for decades to come. (legal example)
2. 2.The decision to offer free shipping was without precedent in the company's history. (prior example)

• example/ɪɡˈzɑːmpl/— an instance serving as a model — broader
• model/ˈmɒdl/— something to be imitated
• benchmark/ˈbɛntʃmɑːrk/— a standard for comparison

from Latin "praecedens" (going before) — same root as "precede"