I'm going to throw out a few observations on Lois Lerner's refusal to testify before Congress, specifically her pleading of the Fifth Amendment. Coyote has an interesting article on the inability of prosecutors to use compelled testimony in legal proceedings, but I think some points have been missed there.
1) Lois Lerner testified, then when asked questions regarding her testimony, pleaded the Fifth. There is an argument, and a pretty good one I think, that you don't get to present your side of the story and then use the Fifth Amendment to avoid any cross examination. She also testified before the Department of Justice. Again, you don't get to testify before a friendly audience and then claim the Fifth to avoid an audience which may be more inclined to disbelieve your testimony.
2) Lois Lerner was an employee of the IRS and the person in charge of those accused of using the IRS for improper political attacks, specifically targeting Tea Party and conservative groups during the run-up to the last presidential election. Your job as the head as a manager at a government agency is to run your part of that agency and report as needed to your boss, in this case Congress as the representatives of the people. If you are going to plead the Fifth when asked about aspects of your job, you should be terminated with prejudice immediately without eligibility for another government job. Ever. That should be considered a de facto admission of guilt.
I have no use for the people who are complaining that she is being unfairly targeted. It is Congress' job to oversee the operations of the government, and if government employees can do whatever they want while in their positions and refuse to testify when called on the carpet, then there is no oversight.