Controversial jockey Danny Nikolic has been accused of being a proven liar and of having a history of enmity to people in authority.
Nikolic is appealing a two-year ban from racing in the Victorian Civil and Administrative Tribunal.
He was disqualified following an incident at the Seymour race meeting on September 4 in which he is alleged to have threatened the family of Victoria's chief steward Terry Bailey.
Phillip Dunn, QC, appearing for Racing Victoria, told the hearing behaviour such as that shown by Nikolic could not be tolerated as it would undermine the industry.
"It is improper and dishonourable behaviour," Mr Dunn said.
He said if Bailey's evidence against Nikolic were accepted, it would be "prejudicial to the interests and welfare of racing".
Nikolic claims he was joking when he told Bailey at Seymour to "keep your eyes on the road".
Bailey claimed that Nikolic also said to him: "We've all got families c--- and we knows where yours live c---."
Dunn said Nikolic was a proven liar whose story changed "like sands sifting through the hour glass".
He said if such behaviour was left unpunished stewards overseeing meetings where Nikolic was riding could have concerns for their welfare.
"They could be reluctant to discharge their duties without fear or favour," Dunn said.
He said that Nikolic was under a great deal of pressure due to recent unfavourable publicity involving him and "felt the walls closing in on him".
Jack Rush, appearing for Nikolic, said Bailey was the one under pressure.
He said Bailey was a man who oversaw a corrupt industry and had not "got a result".
Rush said in light of the slew of media exposure of corrupt activity in racing the stewards were almost a laughing stock."
Nikolic had earlier denied he had threatened another RV steward, Wade Hadley, during a break in a previous VCAT appeal hearing.
But Dunn, who drew on evidence showing closed circuit video film of Nikolic and Hadley seated near each other outside the court room, said it proved a pattern of behaviour in which Nikolic approached stewards then lied about what he had said.
Justice Michael McNamara has reserved his decision.