House Speaker Nancy Pelosi and Democratic senators such as Judiciary Chairman Patrick Leahy who are clamoring for a grand inquiry into CIA interrogation methods should be careful what they wish for.

If they get it, it would likely expose a lot more than the CIA's carefully administered rough stuff on terror suspects. We would certainly learn if such methods saved American lives, as four CIA directors who were around when the methods were used insist they did. We would also learn who in Congress, including Pelosi, were briefed about the methods at the time, and did not object.

Those notorious "so-called" torture memos produced by Justice Department lawyers would certainly get a detailed airing, and the public might well find them an honest and painstaking attempt to find where the line should legally be drawn between toughness and torture.

The lawyers who wrote them would almost certainly prove highly effective witnesses in their defense. In short, instead of bolstering the reputations and careers of the inquisitors, such an inquest could well backfire. Remember the Iran-Contra investigation 22 years ago? A lone witness in his Marine uniform named Oliver North turned the tables on his inquisitors in two days of klieg-lit testimony and made himself an overnight hero.

Senator Leahy should remember that case well. He later lost his seat on the Senate Intelligence Committee after leaking a draft of the committee's final Iran-Contra report.

Brit Hume is the senior political analyst for FOX News Channel.