The inquest into a controversial 2010 raid by elite New Zealand soldiers on a village in Afghanistan has been told some civilians deaths in conflict may be deemed "unavoidable" and legal under international law.
The Government's inquiry into Operation Burnham and allegations six civilians were killed and 15 others wounded during the SAS mission is continuing this week, with experts giving advice about the international laws and treaties that cover the New Zealand Defence Force's conduct in Afghanistan.
Outlining the Crown's summary of the legal framework that applied to the case, Paul Rishworth, QC, told the inquest under international humanitarian law there was a recognised "principle or proportionality" in attacks where civilians could be endangered.
Although the NZDF originally denied civilian deaths, it has since said it cannot rule out some villagers were killed when a gun sight from a US helicopter malfunctioned during the raid.
"The principle of proportionality is a recognition that harm to civilians and civilian property can be the unavoidable result of an attack on a military objective," Rishworth said.
"The test is whether the incidental loss of civilian life … would be excessive in relation to anticipated military advantage."
The standard was based on the "expected" harm to civilians and the "anticipated" military gains and required forces to take "all feasible precautions" to avoid and minimise casualties, he said.
"Accordingly the rule applies as of the time an attack is planned, approved and executed, rather than involving hindsight examination," he said.
"The requirement to take precaution does not equate to a requirement to avoid any attack that might result in civilian casualties."
But journalist Nicky Hager, whose book Hit & Run spurred the probe, on Monday said the NZDF had failed to take the necessary precautions.
"The NZDF-led operation fired into a civilian village and fired at unidentified men in the dark," he said.
Hager and co-author Jon Stephenson also alleged a Taliban fighter, Qari Marj, was caught with the help of the SAS, handed over to Afghan authorities and tortured.
On Monday, former International Court of Justice judge Sir Kenneth Keith also took the inquiry through international human rights and humanitarian law New Zealand troops were subject to.
Sir Kenneth told the inquest - being run by former Prime Minister Sir Geoffrey Palmer and Supreme Court Justice Sir Terence Arnold - precedents in war-crimes trials had found a state could be deemed to be aiding and abetting torture as long as it "knew" what would happen, regardless of intent.
"[The judges] made it clear that knowledge of the wrongdoing was enough," he said, pointing to a 2007 case against Serbia over the Bosnian genocide.
Rishworth disputed this, saying other commentary showed intent was a necessary part of the wrongdoing.
But in either case, there was no evidence New Zealand knew whether the Afghan forces intended to torture Mari, he said.
"That conclusion is sufficient for a resolution of the matter," he said.
But Sir Kenneth raised questions about a 2011 report that had found torture of prisoners by Afghan forces was "systemic".
Hager said the NZDF and Ministry of Foreign Affairs had tried to side-step the issue by pretending Afghan authorities made arrests while Kiwi troops were "just in the vicinity".
"The point of international law is not for countries to find clever ways to minimise and sidestep their obligations; it is to stop people being tortured," he said.
Stephenson and Hager claim the raid was held in revenge for the death of Lieutenant Tim O'Donnel two weeks earlier, but the NZDF says it was targeting two Taliban insurgents at the village.
The inquiry continues on Tuesday.