Dr. James Hansen, Scientist

In case you were wondering he's not a historian. (See Dr. Hansen's piece in the Nation about "Why We Can't Wait" when it comes to global warming.) According to Dr. Hansen (who has been outspoken in his criticism of the Bush administration's policies regarding climate science),

I don't think the Framers of the Constitution expected that when a government employee--a technical government employee--reports to Congress, his testimony would have to be approved and edited by the White House first. But that is the way it works now.

Actually Dr. Hansen, I don't think the Framers of the Constitution expected to have scientists on the federal payroll in the first place.