Perhaps this from the WSJ Blogs gives a good reason:

If there’s any doubt about the importance of getting a record of Senate investigative interviews, consider the case of J. Steven Griles.

Griles, the former deputy Interior secretary, pleaded guilty in U.S. District Court in Washington today to lying to Senate investigators when he was asked about the nature of his relationship with disgraced lobbyist Jack Abramoff, who was trying to help clients on matters before the Interior Department. Abramoff, in prison after pleading guilty to felony charges, has been aiding a wider investigation that has netted eight convictions or plea deals for the Justice Department.

A transcript of the Senate interview is what helped get Griles in trouble. (See the plea agreement.) Former White House aide David Safavian found himself in similar hot water, and was convicted earlier this year on charges that included lying to Senate investigators.

So we have a conviction based upon administration officials lying to Senate and with that we should just “trust them”? Sure and I bet Bush has a war he wants to sell us also!

(h/t TPM)