From the WP, Heeding new counterterror guidelines, U.S. forces backed off in Somalia raid (by Karen DeYoung, October 7, 2013).

First, as to the ROEs:

When Navy SEALs were met with gunfire as they attempted a raid on a seaside militant compound in southern Somalia early Saturday, the commander of the operation had the authority to call in a U.S. airstrike. Instead, he opted to retreat.

The site had been under surveillance, and the operation against an al-Qaeda-affiliated group had been in the planning stages, for months, current and former Obama administration officials said Monday. A drone strike against the al-Shabab compound had been rejected, officials said, because there were too many women and children inside, the same reason that the commander opted against an airstrike once the operation was underway.

Destroying the compound probably would also have defeated a primary purpose of the mission: to capture, not kill, a Kenyan-born al-Shabab commander named Abdulkadir Mohamed Abdulkadir, also known as Ikrima. He has long been on a U.S. “capture or kill” list, along with al-Shabab leader Mukhtar Abu Zubeyr, known as Godane, and was considered the group’s primary planner of attacks outside Somalia.

As they provided more details of the aborted operation in the town of Barawe, current and former administration officials said it was designed within restrictive counterterrorism guidelines that President Obama signed in the spring. Under the 2001 congressional Authorization for the Use of Military Force, the guidelines say that lethal force can be used only when there is a “near certainty that non-combatants will not be injured or killed.”

If civilians had not been present at the compound, a senior administration official said, “we might just as well have done a standoff strike,” hitting the site with missiles launched from piloted or unmanned aircraft. The desire to avoid hitting non-combatants, the official said, “accounts for the fact that ultimately [U.S. forces] disengaged” when they “met resistance.”
If accurate (the actual ROEs haven't been published), the Centcom ROE ("reasonable certainty", given variant meanings) has morphed to "near certainty" - at least in this incarnation. "Near certainty" begins to sound very much like "beyond a reasonable doubt".

That ties in with the second point (both the Somalian and Libyan ops were capture ops):

The guidelines also codify a long-stated but rarely implemented administration preference for capturing rather than killing terrorism targets.

Officials cited the Somalia operation, as well as the capture of an al-Qaeda figure in Tripoli, Libya, on the same day, as proof that the administration is not overly enamored with the relatively risk-free use of drones at the expense of detaining militants to glean intelligence.

“To people who had said we don’t undertake capture operations, here are two,” the senior official said.
No attempt has been made by the administration to justify either operation on other than Laws of War principles. I've no objection to that as such; but, it's interesting that the administration, in effect, recognizes that a state of war exists in the "new" Libya.

Regards

Mike