The son of barrister George Carman, who was hired by Lord Janner in the early 1990s, told ITV News his father once believed the Labour peer would have to face charges over child abuse allegations.
ITV News Social Affairs Editor, Penny Marshall reports.
Dominic Carman says his father felt there had been, "some interference and some pressure brought to bear," after the case was dropped.
The police and the Crown Prosecution Service have admitted it missed four opportunities to prosecute the peer.
Lord Janner has always denied he used his position as an MP to abuse young boys in childrens' homes in Leicestershire, his family have said he is innocent of the allegations against him.