Roosters forward Spencer Leniu has received an eight-match suspension for contrary conduct after calling Broncos half Ezra Mam a "monkey" during the NRL's season opening venture in Las Vegas.

After a 90-minute hearing at the Judiciary on Monday night, the panel returned from deliberations to hand down a unanimous decision rubbing Leniu out of playing until round 10.

NRL legal counsel Lachlan Gyles had pushed for the eight-match ban, with Roosters' parties pleading for four games as enough to send a significant message and within reason for the offence committed.

Leniu had issued an early guilty plea and admitted to using the slur last week.

Mam did not appear after submitting evidence in writing.

In a 12-paragraph submission, the 21-year-old detailed his versions of events, and said he "saw red" after the incident.

Mam is understood to have rejected the offer of an in-person apology from Leniu made last week.

Giving evidence on Monday, Leniu and his counsel argued the use of the word "monkey" was done with no racist intent.

"I thought it was just one brown man sledging another brown man," Leniu said, the Sydney Morning Herald reported.

"I'm happy he brought this up. I have no racial intent towards Ezra or the Indigenous community."

Leniu, who is New Zealand-born and of Samoan heritage, had also said he had been called "monkey" and "coconut" during his life, but was not offended by it.

In the hearing, Leniu said he was not aware of similar cases in Australian sports like the 2008 incident involving test cricketer Andrew Symonds and India's Harbhajan Singh or AFL star Adam Goodes being called an "ape" during a match by a rival team's supporter.

Leniu said he had received backlash to his comment, and had a better appreciation for the hurt caused as a result, including after an older Aboriginal woman "sent me the definition of what monkey means to their people".

Leniu also said he regretted his post-match comments about the incidient.

The panel didn't buy the argument being "satisfied that the player did intend his use of the word "monkey" as a racist comment and did not accept the player's denials to the contrary".

In his summary of the findings, Judiciary chair Geoffrey Bellew wrote Leniu had taken offence to gameplay comments to the effect of "run it at Spencer" made by Mam, "and that he decided to make a racist comment in response".

"The Panel did not accept the player's claimed ignorance that he was not aware that "monkey" was, when used towards the Indigenous community, a racist term. In light of that finding, the Panel was satisfied that the offending fell at a high degree of objective seriousness.

"The simple, and more important fact, is that such a term was derogatory to player Mam."

Mr Bellew said while the panel believed it was unlikely Leniu would commit a similar offence in the future, there was a need to express an "unequivocal view that there is simply no place in the game for racial vilification of any kind, particularly when the player charged is aware of the derogatory nature of the term which is used".

NRL chief executive Andrew Abdo said "Racism and vilification have no place in modern society and will not be tolerated in Rugby League".

"I have spoken to Ezra to commend him for speaking up and taking a stand. It has been warming to see the game rally around him during this time," Abdo said.

"I also acknowledge Spencer Leniu's genuine remorse and apology and ask everyone to consider his wellbeing after a testing time in his young career. We are human beings and we make mistakes. That is how we all learn and grow.

"The penalty applied tonight underscores the zero tolerance rugby league has for racism. From this sad event some important lessons can be learned."

Roosters chief executive Joe Kelly said the club accepted the decision, and that they would support Leniu to "increase his education about the Aboriginal and Torres Strait Island Cultures".

"On behalf of Spencer and the Sydney Roosters we apologise unreservedly to Ezra and his family for the hurt that has been caused and we extend this apology to the wider Aboriginal and Torres Strait Islander community," Kelly said.

"Inclusivity and diversity are key and fundamental values of the Sydney Roosters and we respect equally all backgrounds and cultures and will not tolerate any form of racism."

Kelly reiterated there was - in his view - no racial intent behind Leniu's remark.