extraordinary appeal; emergency appeal
A special appeal to the Supreme Court of Japan, filed by the prosecutor-general when a final judgment is believed to be in violation of law. Rare in practice.
An extraordinary appeal is a special procedure in which the prosecutor-general petitions the Supreme Court against a final judgment on the grounds of a legal violation.
A standard appeal to the Supreme Court, whereas 非常上告 is an extraordinary appeal filed by the prosecutor-general after a judgment has become final.
A retrial based on new facts, while 非常上告 is based on legal errors in a final judgment.
Compound of 非常 (emergency, extraordinary) and 上告 (appeal to a higher court). The term is a direct legal borrowing from the concept of extraordinary appeal in civil law systems.