The international co-investigating judge at the Khmer Rouge tribunal ruled on Tuesday that an attack by a government on its own soldiers can be considered an attack on a civilian population, and therefore can constitute a crime against humanity.

The debate arose in regards to a line in Article 5 of the law establishing the tribunal, which defines crimes against humanity as “Atrocities and offenses, including but not limited to murder, extermination, enslavement, deportation, imprisonment, torture, rape, or other inhumane acts committed against any civilian population.”

The judge, Michael Bohlander, made the decision after extensive input from the defence teams, the prosecutor’s office and other legal experts.

“Civilians should be defined as those who cannot be lawfully or legitimately targeted in an armed conflict … which would include those members of the armed forces who are … not acting adversely to their own governments,” Bohlander wrote in a statement published on Wednesday.

However, an attack on soldiers will not be classified as a crime against humanity if those soldiers were “allied with or otherwise providing militarily relevant support to an opposing side in an armed conflict”.

The prosecution supported the decision, while the defence teams for suspects in Cases 003 and 004 Meas Muth, Ao An and Yim Tith all objected. The ruling was made in regards to Case 003, featuring Meas Muth, but may have ramifications for the other suspects as well.

“Our position was that the ‘civilian’ requirement was meant to exclude attacks against other militaries … but it was never meant to exclude attacks against one’s own military personnel. Just because someone is a soldier does not mean their government can commit crimes against them with impunity,” said prosecutor Nicholas Koumjian.

Koumjian added that otherwise, a government regime could simply draft any undesirables into the army, and then “do with them as they please”.

Koumjian also said the term “allied with” was possibly too vague, but that there was no “credible evidence” that Khmer Rouge victims were working with enemy forces.

Michael Karnavas, defence lawyer for Meas Muth, while praising Bohlander’s character, disagreed with his conclusions.

“Reasonable legal minds can reasonably disagree,” Karnavas said, adding that his team still retained the right to challenge the appealable decision.

Karnavas took particular issue with Bohlander’s argument in his decision that post-World War II tribunals did not specifically inquire as to whether victims were soldiers or civilians, thus justifying equal legal treatment, a position Karnavas said he found unconvincing.