If the NY Times is correct about that rule, General Huck is probably as rightly frustrated as anyone would be when you have to fight a war with rules as arbitrary as those. I wonder if they run those investigations in the Air Force?
I guess he is supposed to run the calculation for every firefight, IED explosion, etc. And if the US casualties happen to be low enough then he investigates. Imagine if this attack had been more of a success for the enemy - then he wouldn't have to investigate. Sounds totally backwards to me. I would think he should investigate what went wrong when there are a lot of US casualties, not the opposite!
The proper test for assessing whether an attack led to excessive civilian casualties can't be just a numerical ratio, but depends on the overall circumstances, but even if it was, the ratio should be enemy combatants killed to civilian casualties.
The General should have 100% of his attention on winning, not following bureaucratic rules that look like they were drafted by some guy at a the SEC or IRS, or Congress.