43 CAP. 224 Penal Code 2008 Ed. Act done by a person justified, or by mistake of fact believing himself justified by law 79. Nothing is an offence which is done by any person who is justified by law, or who by reason of a mistake of fact and not by reason of a mistake of law in good faith believes himself to be justified by law, in doing it. Illustrations (a) A sees Z commit what appears to A to be a murder. A, in the exercise, to the best of his judgment exerted in good faith, of the power which the law gives to all persons of apprehending murderers in the act, seizes Z, in order to bring Z before the proper authorities. A has committed no offence, though it may turn out that Z was acting in self-defence. (b) A, a police officer, is deployed to perform the duty of screening passengers boarding a flight at the airport. A sees Z, a passenger queuing up to be screened, acting suspiciously. As A approaches Z, Z suddenly shouts aloud that he is carrying a bomb and warns A not to approach further. As A draws his revolver, Z suddenly starts to run away. A, after assessing the circumstances of the case, and to the best of his judgment exerted in good faith, believes that Z has a bomb and will set it off. A shoots Z and Z dies as a result. A has committed no offence, even though it may turn out that Z was not carrying a bomb. (c) A, a police officer, is deployed to perform patrol duty at an underground train station. A receives information from police headquarters that someone is attempting to plant a bomb in the public transport system. The profile of the suspect is also provided. While patrolling the underground train station, A sees Z, who fits the profile. Z is seen carrying a backpack and behaving suspiciously. A approaches Z and orders him to stop. Z suddenly starts running towards a crowd in the station. A, after assessing the circumstances of the case, and to the best of his judgment exerted in good faith, believes that Z has a bomb and will set it off. A shoots Z and Z dies as a result. A has committed no offence, even though it may turn out that Z was not carrying a bomb. (d) X, the commander of a naval vessel, is patrolling Singapore territorial waters. X receives information that someone may hijack a vessel in order to commit a terrorist act. X spots vessel A which is proceeding at high speed towards a cruise liner. X orders vessel A to stop her manoeuvre immediately and fires a warning signal. Vessel A instead starts accelerating towards the cruise liner. X, after assessing the circumstances of the case, and to the best of his judgment exerted in good faith, believes that vessel A is going to ram into the cruise liner. X Informal Consolidation – version in force from 1/4/2015