From Article II, section 2 of the United States Constitution:
"The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States; he may require the Opinion, in writing, of the principal Officer in each of the executive Departments, upon any Subject relating to the Duties of their respective Offices, and he shall have Power to grant Reprieves and Pardons for Offences against the United States, EXCEPT IN CASES OF IMPEACHMENT. (my emphasis)

Article II Section 4:
"The President, Vice President AND ALL CIVIL OFFICERS (my emphasis) of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors."

Gonzales is indeed a "civil officer", who takes the oath to protect and defend the Constitution.

I know it's a longshot, but it might be the only shot at restoring the integrity and protecting the longevity of the Constitution and our form of government, and getting any kind of accountability for the crimes of the Bush administration:

If Alberto is impeached and cannot be pardoned, he will have to cut an immunity deal and sing his ass off to stay out of prison. And it's pretty clear, given his years of association with George, that he knows EVERYTHING, which is most likely the ONLY reason he still has his job in the face of the incredibly bad DOJ PR that Dubya and Uncle Dick strangely seem all too willing to endure.

Alberto first, then Cheney, then Bush. And let's get them all impeached and removed before any criminal charges are filed, so the next president will not be tempted (politically suicidal as it may be - just ask the late Gerald Ford, who pardoned Nixon) to pardon them.