Reply #4: It depends

[TechBear_Seattle]

Impeachment can not be pardoned, as you pointed out. However, impeachment is limited to removal from office only; it is not a criminal trial. Once a sitting president or vice president is removed from office -- for any reason, be it resignation, impeachment or expiration of term -- he is subject to criminal indictment and trial for criminal activity that might have been done while in office. That is why Ford pardoned Nixon: to proactively avoid an investigation and criminal trial, which would have been totally unrelated to the impeachment itself.

So Bush and Cheney can not use the pardon to avoid impeachment, but they can use the pardon to avoid criminal prosecution once they are out of office.