From what I read in the excerpts of Steve Coll's book Ghost Wars, virtually every attempt to capture OBL was waylaid by the tortuous legal blockades erected by the Reno DoJ (including Gorelick).
For example, according to Coll, the CIA ground troops and its task force had OBL nailed several times, and in each instance the DoJ came back with some sort of twisted authorization that would basically leave individual CIA exployees to swing in the wind should anything go wrong. In each instance, the Adminstration would assume no responsibility whatsoever, and the "authorization" memos were written in that vein.
I found it perfectly logical that when Reno herself appeared before the 9/11 Commission, within 10 minutes she had declared that she couldn't recollect what was and was not classified, so for the remainder of her testimony they threw her nothing but softballs. Not once was the issue of these autorization memos discussed or questioned.
And lets not forget the time they could have gotten OBL but Clinton was talking to people on the golf course and wouldn't be interrupted.