I've never been clear on what specific charges Lerner would face. Abuse of power under the color of authority? Or some sort of conspiracy charge to deny equal treatment/rights under the law and Constitution?
She used her position to do a hatchet job on political opponents of Democrats. But the purpose of the IRS is to administer and enforce tax legislation. She had no authority to do what she did. She went out of bounds of the authority entrusted to the IRS. What she did was illegal. People have lost their pensions and/or are in jail for less than what she did.