Supreme Court, Second Petty Bench · October 16, 2026 · Reiwa 7 (2025) (A) No. 137 · Judgment; judgment below reversed and the appeal dismissed

The Court reversed a judgment that had found a factual error in a first-instance judgment recognizing the negligence of a boat operator, holding that the judgment below misapplied Article 382 of the Code of Criminal Procedure, and dismissed the appeal.

Professional negligence resulting in death or injury (criminal case)

Facts

The defendant, as captain of a pleasure motorboat, was navigating on a lake at about 15 to 20 km per hour when the rotating propeller struck victims floating ahead of the boat. One person died and two were injured, and the defendant was prosecuted. The first-instance court found negligence on the ground that, had the defendant kept a strict lookout ahead, he could have seen the victims as floating objects before they entered the boat's blind spot, confirmed whether they were persons, and avoided the collision; it sentenced him to imprisonment without work for two years. The court of appeal held that the first-instance judgment contained a factual error because it could not be said that the defendant could have detected the victims as persons, quashed it, and entered an acquittal.

Issue

What must a court of appeal show in order to find a factual error in a first-instance judgment? Was the first-instance finding that the defendant could have seen the victims as floating objects unreasonable?

Ruling

The Court held that the grounds of final appeal did not fall within Article 405 of the Code of Criminal Procedure and examined the case on its own authority. It held that a factual error under Article 382 means that the first-instance fact-finding is unreasonable in light of the rules of logic and experience, and that a court of appeal must concretely show such unreasonableness (citing the judgment of the First Petty Bench of February 13, 2012). It then held that the judgment below rejected the first-instance finding on the boat's course without sufficient basis; that its suggestion of the course by joining parts of the records of two mobile phones, whose position data for the same times differed considerably, was contrary to the rules of logic; and that it did not grasp the structure of the first-instance inference from multiple indirect facts and merely pointed to the possibility that the victims could not have been detected at individual points or moments. The Court concluded that the judgment below could not be regarded as having sufficiently shown that the first-instance fact-finding was unreasonable. It reversed the judgment below, upheld the first-instance judgment recognizing negligence, and dismissed the appeal. The opinion was unanimous.

Provisions

Code of Criminal Procedure, arts. 382, 411(i), 413 proviso