How can Trump call Cohn his "greatest friend"?
Extremely bad judgement.
But the question is : what have this lot got on Trump?
What used to happen in the basement of Studio 54?
Dick Morris is a product of the Roy Cohn criminal apparatus, which was created to do political dirty work for the "white glove" British and allied New York banking oligarchy, represented in person by Thomas E. Dewey and the Dulles brothers. The inherited power and sleaze of this family apparatus landed Dick Morris his first job, working for the biggest Anglo-American bankers at the Citizens Budget Commission in New York from 1967-74. The nature of the beast may be glimpsed in the sordid web tying together Dick's father, Eugene J. Morris, Eugene's first cousin Roy Cohn, and the underworld of the legal and political communities.
In 1965, Eugene Morris became part of the leadership team at the New York Law Journal, editing a weekly column which he often himself writes. The Journal is a Cohn family preserve: given tremendous clout and status as the official daily newspaper of the legal profession by decree of Judge Albert Cohn (Roy's Cohn's father, Eugene Morris's uncle) and his bench partners, and owned since at least 1963 by Roy Cohn's business and political partner and client, Jerry Finkelstein, and his son James Finkelstein.
...1935-37: Thomas E. Dewey (later New York governor) is positioned to control vast Mafia networks as New York special prosecutor and "investigator of organized crime." Jerry Finkelstein serves as staff assistant to Dewey.
1940s: Governor Dewey releases Meyer Lansky's partner Charles "Lucky" Luciano from prison to re-create the Mafia under Anglo-American intelligence control.
1957: Former Governor Dewey organizes the World Peace Through Law organization-lawyers representing Anglo-Saxon bankers-at a meeting in London of the American Bar Association under the direct supervision of the British Crown and government (in meetings with Queen Elizabeth II and Prince Philip and the Privy Council), in conjunction with U.S. Solicitor General J. Lee Rankin, a former Dewey staff member.
1957: Dewey's personal representative, Judge David Peck, arranges for Sen. Joe McCarthy's disgraced lawyer Roy M. Cohn to be placed in the New York law firm of Saxe, Bacon and 0' Shea. Cohn takes over the firm, bringing in such clients as the Gambino family, the Finkelsteins, and Lansky partners such as Schenley's liquor boss Lewis S. Rosenstiel.
1958: Dewey's Crosby-Miller company takes over the Mary Carter Paint company, which, with the Dewey cover, is used by the Lansky mob to open up Caribbean gambling operations and drug-money laundering. British legal authorities help clear away Caribbean gambling rivals of Mary Carter Paint, which in 1966 becomes Resorts International, later notorious as Murder, Inc.
1963: Roy Cohn, a murderous enemy of the Kennedy family, is deeply implicated in the Permindex organization which New Orleans District Attorney Jim Garrison targets as central to the John F. Kennedy assassination. J. Lee Rankin serves as chief executive of the Warren Commission covering up the assassination.
...1967: New York Mayor John V. Lindsay, aided by his Corporation Counsel J. Lee Rankin and the Ford Foundation, launches a crusade for budget austerity and the destruction of labor unions, beginning in New York as a national model for the Conservative Revolutionaries. Two chief instruments for this bloody war were the Citizens Budget Commission (CBC), run by Morgan and other bankers (Mayor Lindsay's brother was Morgan Guaranty executive vice president and later its president), demanding budget slashing and government decentralization; and the Citizens Union, propagandizing for an end to pro-growth constituency forms of political control.
[source : Morris and the Cohn family criminal gang, EIR, http://www.larouchepub.com/eiw/public/1996/eirv23n28-19960705/eirv23n28-19960705_056-morris_and_the_cohn_family_crimi.pdf, 5th July 1996]