The game's boss took the stand in the Federal Court on Tuesday as the St George Illawarra forward's challenge to the game's "no fault" stand-down policy continued.

De Belin is suing the ARL Commission and the NRL after he was stood down under the game's controversial new rules which were penned on February 28 and rubber- stamped in March.

De Belin's barrister Martin Einfeld grilled Greenberg on his motivations for introducing the new rules.

Despite sitting in the court in the morning, De Belin was not present during Greenberg's two hours of testimony in the afternoon.

The Dragons star was stood down indefinitely after he was charged with the aggravated sexual assault of a 19-year-old woman.

He has pleaded not guilty and the case is scheduled to be mentioned in Wollongong Local Court on Wednesday.

Under the "no fault" rules, the game can stand down any player charged with a serious crime which carries a jail term of 11 years or more.

Einfeld argued that Greenberg and the game had no right to stand him down given they had no evidence of his conduct.

"The only evidence I had was the charge he was facing," Greenberg said.

Einfeld pointed to a February 27 tweet by ARL Commission chairman Peter Beattie in which he said: "De Belin is innocent unless proven guilty. Neither I, nor the ARLC & NRL are in possession of any evidence that enable us to form a view on this matter."

Greenberg responded: "Our chairman does tweet a quite a bit."

The day prior to the February 28 ARL Commission meeting during which the rules were drafted, Greenberg met with De Belin at St George Leagues Club at Kogarah.

It was there that he urged him to stand down on his own so that the game did not have to impose a ban.

Greenberg presented the NSW State of Origin lock with a draft statement written under De Belin's name which he himself could release in the hope that it would convince him to step away from his playing duties voluntarily.

"I was hopeful in my discussions that he would see merit in making the decision himself," Greenberg said.

"If that was his position, I could assist him with the narrative publicly.

"But it was clear in my discussions that was not his position."

Greenberg argued that he acted to protect the image of the game, corporate support, broadcast revenues and participation rates, in particular female player numbers.

Pushed on whether the misbehaviour of NRL players would affect the attitudes of the game's 175,000 male and female participants, Greenberg said: "I would absolutely assert that is the case."

Greenberg's testimony will continue on Wednesday.

AAP