Frankly, IntelTrooper's point disturbs me more than any ROE questions... but on to the ROE question. I'm not writing what follows for the benefit of folks who know (aka regulars here), but threads like this one tend to draw the attention of folks who don't (aka visitors via Google, etc), so I think it worthwhile to add this.

From the publicly released portion of Gen McChrystal's tactical directive:
The use of air-to-ground munitions and indirect fires against residential compounds is only authorized under very limited and prescribed conditions (specific conditions deleted due to operational security).

(NOTE) This directive does not prevent commanders from protecting the lives of their men and women as a matter of self-defense where it is determined no other options (specific options deleted due to operational security) are available to effectively counter the threat.

I am not privy to those other specific options and conditions - so I'm speaking on generic terms. Here's the quote from the story that's generating the heat:
U.S. commanders, citing new rules to avoid civilian casualties, rejected repeated calls to unleash artillery rounds at attackers dug into the slopes and tree lines — despite being told repeatedly that they weren't near the village.
I'm left to wonder if the radio response from the TOC was "sorry, no can do - ROE says so" - or if not, how this explanation made its way into the story. If I can think of a dozen ways that could happen I'm sure others can, too.

Some of those "ways" include an accurate characterization of the decision process. Which - if that's what it is - reads to me like a misinterpretation of ROE. ("...despite being told repeatedly that they weren't near the village...") One would hope (and I think this approaches Niel's point) that errors on the side of caution would favor the guys on the ground. But obviously one could argue that (assuming the case is as described) errors in this case favored the bad guys.

None of that indicates the ROE themselves are "bad" - to make that determination we'd need to examine those specific options and conditions - something the guys who made the on-scene decision did, and something those who will officially review this incident will also do.

FWIW: in this case it appears the four Marines were killed in the opening moments of the attack prior to the request for fires, this is not to downplay the issue but to clarify that we are not talking about an incident where any US troops died as a result of whatever decision was made regarding IDF/CAS.

On the other hand, there are other troubling aspects to the (as-told) story of a unit walking to a village (where elders had "announced over the weekend that they were accepting the authority of the local government") at a pre-arranged time to meet, greet, and conduct searches of homes that we haven't delved deeply into.

Meanwhile
Pentagon spokesman Geoff Morrell said that it did take “some time” for air support to arrive, but the delay was due to distance, not the rules of engagement.

He said the deaths are under investigation, adding, “We will hopefully get to the bottom and figure out if everything operated according to protocol.”

Honestly, I'm glad the attention is being paid. Clarity is a good thing.