The presidential pardon power is absolute, clearly spelled out in the Constitution. It cannot be overridden by any means.
Don't be naive. They can hair split the Pardon to death, and prosecute for things that are technically not covered by it.
If they don't prosecute her for abuse of office, they can prosecute her for misusing government resources. Losing paper clips. It does not matter. They will make the crime fit the limits of the pardon because there is so much leeway in the law, they can make criminals out of people when they want to.
Lois Lerner needs to be prosecuted, and like Al Capone, if you can't get someone for murder, extortion and illegal manufacturing and distribution, you can get them for tax evasion.
It does not matter much on what charge Lois Lerner gets sent to prison. It is simply necessary that Lois Lerner go to prison to serve as an example of what happens to a government official abusing their office with the connivance of their superiors.
As "Remo Williams" said of the 11th commandment.
"Thou shalt not get away with it."
The pardon power pertains to federal crimes, IIRC. States could prosecute under state law.
Maybe I’m wrong but it seems to me the 10th Amendment would be in play.
“The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” -
See more at: http://constitution.findlaw.com/amendment10.html#sthash.Gb2FI8Ou.dpuf