Gorelick wrote the "wall of separation" memo that kept military intelligence agencies from talking to FBI officials. Her memo was directed at the Director of the FBI and told him and his agency what they could not do.
In short, Gorelick's memo contributed to the bad result in this situation, and presumably others. She should never have been a member of the Commission. Instead, she should have been sworn as a witness and cross-examined under oath.
She is why the Commission didn't deal with this subject in its report. And she definitely doesn't want an investigation that will find her fingerprints on this failure of intelligence about Mohammed Atta.
Congressman Billybob
http://hnn.us/articles/11972.html
The above link will take you to a most interesting, in-depth description of the 9-11 Commission.