He is reputed to have an encyclopedic knowledge of criminal law and has argued over 100 cases before the Supreme Court. Harold Koh, the former Obama administration legal adviser to the State Department, worked with Dreeben and compared him to NBA superstar Shaquille O'Neal. Koh described Dreeben to ABC News as "the best in the business ... [he's] the best appellate criminal law specialist in the country." On May 4, Dreeben sparred in court with federal Judge T.S. Ellis during a hearing over dismissal of the 32-count indictment against Manafort.