South Sydney hooker Issac Luke will miss Sunday's NRL grand final against Canterbury after the judiciary upheld his one-match ban for a dangerous throw on Tuesday night.

Luke bowed his head and looked at the floor after the verdict was read out by judiciary panel member Mal Cochrane, who spent 11 minutes deliberating with the two other panel members Chris McKenna and Michael Vella.

Judiciary chairman Paul Conlon echoed the thoughts of all Souths fans, officials and players when he immediately addressed Luke.

"We all know what that means," he said.

"It is very unfortunate."

Luke declined to comment as he left League Central following the decision.

Rabbitohs coach Michael Maguire didn't answer questions from the reporters and cameramen assembled but only gave a short statement.

"Obviously not the result we were after," Maguire said. "But I know I have a squad that are looking forward to preparing well all week and getting into Sunday's game."

Penrith-bound back-up rake Api Koroisau filled in capably for Luke earlier this year when the 27-year-old suffered a shoulder injury, and is likely to be called upon again to fill his role in the decider.

Luke was hit with the charge following a 38th minute tackle on Sydney Roosters forward Sonny Bill Williams in the Rabbitohs' 32-22 preliminary final win over the premiers at ANZ Stadium on Friday.

With the guilty verdict, Luke is hit with 200 penalty points, with 100 points equalling a one-match suspension, meaning he will also miss the Kiwis' opening Four Nations match against Australia in Brisbane on October 25.

From the outset judiciary prosecutor Peter Kite argued the tackle on dual international Williams was "a classic grade one dangerous throw".

"There was an unacceptable risk of injury," he continued.

"The position player Williams was put in meant his head or neck could have been the first contact point with the ground. A dangerous position was achieved."

Souths defence counsel Nick Ghabar countered that Luke's tackle, which also involved back-rower Ben Te'o, was a "conventional rugby league tackle, some might say a copybook rugby league tackle".

Ghabar argued Williams contributed to the way the tackle ended up as he skipped and then he "contorted" in the tackle and pulled down on Luke's shorts as he looked to offload the ball.

"The skip combined with the yanking of the shorts produced an elevation," he said. "It was an awkward, innocuous landing. There was no acceptable risk of injury."

Ghabar also argued that Te'o contributed significantly to the position Williams ended up with, a point of difference with Kite.

"Player Te'o substantially contributed," Ghabar said.

But the three-man panel agreed with Kite's assertions and Luke, who has been with Souths since 2007 and played 168 NRL games with the club, will miss the biggest game of his career and the Rabbitohs' first grand final since 1971.

Luke took to Instagram shortly after leaving Rugby League Central to express confidence in his teammates.

"Not the result we were after," he wrote.

"Can only feel stronger for my brothers that will take the battlefield.

"Now to focus on our game this weekend. SSTID [South Sydney til I die]. Love you's all make sure all your fans get out there.

"Support this great game we love.

"Devastated but at the same time excited to still be part of this amazing journey. Time to rip little brother apikoroisau.

"I got your back g." AAP