When working in the field of accicent analysis - what NTSB does - you are always confronted with legal aspects, liability, recommendations and so on.
Another very interesting approach is done by Hollnagel with the FRAM (functionl resonance analysis method):
fram (erikhollnagel2) or
http://www.skybrary.aero/bookshelf/books/402.pdf
In my point of view this method gives a very deep view into sociotechnical systems even it's not too simple to apply. And I think it also fits a litte bit more to the idea that often there are many "root causes". For me, I define a "root cause" as one single thing, so for me this concept is not sufficient to describe several contributors which lead in common to an accident.