I'm not sure what that even means. Are you suggesting that the U.S. Attorney General or Deputy AG aren't allowed to appoint their own subordinates?
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Rosenstein was not vetted and approved as per the constitution, thus he cannot make the appointment.
Simple.
Going after the corrupt is long overdo and in particular the two mentioned in this thread. Punishments need to be VERY SEVERE, thus sending a signal there’s a new sheriff in town and there are laws that even those two are subject to. There should be NO EXCEPTIONS. Once these two are fitted for their orange suits, go after the low hanging fruit (Hitlary for example). Time for settlements.