Lois Lerner invoked her Fifth Amendment right not to answer questions from Congress .
Lois Lerner 's at the center of the political firestorm over her agency 's singling out of some conservative groups for extra scrutiny .
Lois Lerner , who 's at the center of the political firestorm over her agency 's singling out of some conservative groups for extra scrutiny , invoked her Fifth Amendment right not to answer questions from Congress .