The rationale for having the right of Private Defence was that while the state had a duty to protect its citizens from unlawful force, there were times when this was not possible and the citizens were empowered to take such measures as were reasonably necessary to counter an unlawful force.
The provisions related to Private Defence can be found in the Singapore Penal Code from Section 96 -106.
A person has a right of private defence against an attack. While this seems simple in theory, it may be more complicated in reality. In the case of Roshdi v PP, the Victim had attacked the defendant, and was choking the defendant whose back was against the wall. The victim then reached for his revolver. The defendant was fearful for his life and used a heavy mortar to strike the victim several times on the head, killing him. The court held that the defendant applied more force than was necessary. This was despite the victim being of a stronger physique than the defendant.
In contrast, the case of Ngoi Ming Sean involved a defendant who was being accosted by the victim. The victim was chased behind the bar counter and to the toilet exit. In an attempt to defuse the situation, the victim warned that he was a police officer. To prove that, he pulled out his revolver with one hand, and held his authority card with the other. However, the victim charged and the defendant shot the victim in the chest, killing him. The court held that the defendant’s response was necessary, noting that the victim was physically bigger than the defendant.
Academics have preferred the more generous test in Ngoi Ming Sean as to what constitutes a reasonably necessary response. It is likely that Singapore courts will follow this approach, though the stricter approach in Roshdi may be followed instead. If you have had to exercise your right of private defence, it is best to seek advice from a criminal lawyer as to whether your response constitutes what was reasonably necessary. The lawyer will also be able to advice you on the criminal proceedings that may follow.