 The Beck and Hoffa hearings generated strong criticisms of Robert Kennedy . Many liberal critics said he was a brow @-@ beater , <unk> , insolent , overbearing , intolerant , and even vicious . Hoffa and other witnesses often were able to anger Kennedy to the point where he lost control , and would shout and insult them . Supreme Court Justice William O. Douglas , one of Robert Kennedy 's mentors and a close friend , criticized Kennedy for presuming the guilt of anyone who exercised his Fifth Amendment rights . Noted attorney Edward Bennett Williams accused the Select Committee of bringing witnesses into executive session , ascertaining that they would exercise their Fifth Amendment rights , and then force them to return in public and refuse to answer questions — merely to generate media attention . The Chicago American newspaper so strongly criticized Robert Kennedy for his overbearing , zealous behavior during the hearings that a worried Joseph P. Kennedy , Sr. rushed to Washington , D.C. to see for himself if Robert Kennedy was endangering John Kennedy 's political future . 
