Instead, it’s thrown out any time an act of war appears to be particularly unfair or evil, often without full context or detail.

I often see news reports being quite careful and describing what appears in detailed evidence documenting murder by the military as 'apparent' war crimes.

I would argue that the credible accusation of war crimes, that is, with evidence available, requires a full investigation and trial full stop. If no trial occurs, and nobody sues for defamation, the papers can say whatever they feel confident enough to say. Except WikiLeaks...

In Australia there was the interesting defamation case recently with a civil court finding that the soldier who brought the defamation case had no case and did in fact commit war crimes in Afghanistan. He has not been charged with a crime. What does this say about impunity for war criminals? In contrast, Australian military whistleblower David McBride had to plead guilty last month for releasing evidence of war crimes and their cover-up by military leadership to a journalist with the state-broadcaster, the ABC. In both cases though, the news organisations publishing the news articles are seen to be in the right by the government and courts. (Although the ABC did get raided just a couple of months after Julian Assange was dragged out of the Ecuadorian Embassy, the journalist was not charged.)