(Assuming it's the same as aviation, with which I'm very familiar), NTSB factual reports are the only reports admissible into court. NTSB preliminary and final reports, which are the ones which contain findings or probable or contributing causes are statutorily barred from being admitted into evidence of other trials. (This is to encourage open participation from potential parties to future lawsuits.)
Hugely sensible policy, I think, that contributes to the amazing safety record of aviation. I wonder whether it's the same for other modes of transportation.
