Ray McGovern at Consortium News had an opinion that got him booted out of the hearings with General Patraeus.

If memory serves, the aforementioned generals and Westmoreland were required to testify under oath. And this was one of the main sticking points when CBS aired a program showing that Westmoreland had deliberately dissembled on the strength of Communist forces and U.S. “progress” in the war.
When Westmoreland sued CBS for libel, several of his subordinates came clean, and Westmoreland quickly dropped the suit. The analogy with Westmoreland—justifying a White House wish to persist in an unwinnable war —is the apt one here.
If Petraeus is so honest and full of integrity, what possible objection could he have to being sworn in?

No one seems to swear to the truth anymore.