Omri Abu, an officer in Israel's Border Police, was travelling in a bulletproof vehicle four years ago when it came under a barrage of stones thrown by Palestinian demonstrators as it drove through the West Bank village of Na'alin.
He opened the door of the SUV and shot twice, striking 10-year-old Ahmed Moussa in the forehead, killing him instantly.
What is being decided in an Israeli court is whether Mr Abu is guilty of negligence by firing his weapon.
In the trial's closing arguments that began last week, Mr Abu insisted that using his gun was the only responsible course in dealing with the Palestinian demonstrators.
"If they see you don't respond, it will be seen as a weakness," the Israeli daily Haaretz yesterday quoted him as telling a magistrate court in the city of Ramle.
He added: "If they see you don't respond they can crowd around us and the incident can escalate to 1,001 other possibilities."
Taking issue with the notion that stones posed a dire threat, Mr Abu also said bulletproof vehicles "are only protected to a certain level".
Other border police present at the time differ with Mr Abu.
They testified that Israeli security forces were not in danger at the time of the shooting. Mr Abu fired on his own volition, his commander testified.
Closing arguments are to resume next week, although it is unclear when a verdict will be issued.
Front Page Features