Wyeth points out that tipping off Gonzales of the White House investigation is itself potentially a violation of law.

The first rule of scandal is that the cover-up is worse than the crime. With that in mind, we ought to be looking to see if any effort was made to prevent the CIA from requesting a Justice Department investigation. And we ought to find out who warned the White House Counsel that something was up, so that Alberto Gonzalez could warn the White House staff in his now famous e-mail.
There is ample precedent for this. In fact, a similar "Heads-Up Gate" cost Roger Altman his job during the Whitewater scandal.

Testifying before the Senate banking committee in February 1994, then-deputy Treasury Secretary Roger Altman (a college friend of Clinton's) conceded he had given top White House officials, including then-White House counsel Bernard Nussbaum, a "heads-up" on nine RTC criminal referrals that in one instance targeted Clinton's 1985 gubernatorial campaign, and named the Clintons as witnesses in others. (From CNN's History of Whitewater)

Six months later, Altman was back before the Senate Banking Committee. Three weeks after that, it resigned in disgrace.