Everything is refutable by people who who don't like truth. Sounds like you may be among the "Saddam had WMD" crowd so you may have some personal experience with what I'm talking about.
I apologize that this doesn't all fit on a bumper-sticker, and I don't have the use of crayons .. however, if you follow the bouncing ball ...

 .. Sibel Edmonds .. Here's what she had to say ..
http://www.wanttoknow.info/sibeledmonds

 .. On October 18, 2002 John Ashcroft asserts a rare state secret privilege which amounted to a gag order on Congress and Sibel Edmonds. This prevented the Senate Judiciary Committee from conducting public hearings and Senator Orin Hatch blocked closed hearings on the matter. Ashcroft's gag order also prevented Sibel from testifying in her own suit against the FBI and other suits filed by 9/11 families and the Project on Government Oversight (POGO).
Classified Letters Regarding FBI Whistleblower Sibel Edmonds
http://www.thememoryhole.org/spy/edmonds_letters.htm
Effectively Congress gagged from discussion of Edmonds testimony.
Also gagged are the employees at United and American Airlines (whose planes were involved), victims' family members, media reps who have reviewed pertinent classified material, FAA employees, FBI employees, fire-fighters, police officers, and first-responders have all been officially gagged and restricted from talking or reporting to the press and Congress.
Feel free to research this with Fox News or whatever source you feel comfortable with.