A single internal Department of Justice email could be the smoking-gun document in the Operation Fast and Furious scandal — if it turns out to contain what congressional investigators have said it does. The document would establish that wiretap application documents show senior DOJ officials knew about and approved the gunwalking tactic in Fast and Furious. This is the opposite of what Attorney General Eric Holder and House oversight committee ranking Democratic member Rep. Elijah Cummings have claimed. It appears that email would also prove senior DOJ officials, likely including Holder himself, knew in March 2011 that a Feb. 4, 2011 letter...