An established fact or fait accompli—something already done and difficult to reverse. Often used in political or negotiation contexts.
彼らは契約を急いで進め、既成事実を作ってしまった。
They rushed the contract and created a fait accompli.
政府はその計画を既成事実として発表した。
The government announced the plan as an established fact.
交渉の前に双方で既成事実化を避けるべきだ。
Before negotiations, both sides should avoid creating faits accomplis.