Holder is responsible for murder of a federal agent, suborning perjury of federal officials, committing perjury, refusing to comply with numerous subpoenas, money laundering and allowing drug gangs to operate freely in the U.S. The members of Congress have sworn to uphold and defend the constitution. They have a duty and an obligation to impeach and prosecute Holder, Napolitano, Obama and all other administration officials responsible for these acts.
It's as simple as that.