expression
in time of need; should an emergency arise
A formal, somewhat literary set phrase used to refer to a hypothetical future crisis or emergency. Often appears in discussions of preparedness, national defense, or contingency planning.
一朝有事の際には、国民の安全を守るための対策が求められる。
In the event of an emergency, measures to protect the safety of the people are required.
彼は一朝有事に備えて、常に準備を怠らない。
He is always prepared for any contingency.
緊急時 is a more common, neutral term for 'in an emergency,' while 一朝有事 is a formal, literary set phrase with a nuance of a sudden, unforeseen crisis.
A yojijukugo (four-character compound) combining 一朝 (one morning, suddenly) and 有事 (emergency, contingency). The phrase literally means 'one morning, an incident occurs,' conveying the idea of a sudden crisis.