New Zealand Warriors captain Micheal Luck has slammed the National Rugby judiciary after Johnathan Thurston escaped a detrimental conduct charge.

North Queensland skipper Thurston is free to play against South Sydney on Monday despite an expletive-laden attack on referee Jason Robinson for not ruling a forward pass late in the Cowboys' 24-20 loss to Manly on Saturday.

Luck was incredulous the star halfback had not been punished, suggesting Thurston's status in the game had protected him.

"I can't believe they let him off," he told Radio Sport.

"It's set a pretty dangerous precedent now that anyone who sprays the ref can go back to that incident and say 'well, Thurston didn't even get penalised, why am I at the judiciary?'

"Any other player on the field that night, or any team, would have been at least penalised."

Former Cowboys forward Luck said had learned to mind his language since referees had been fitted with microphones and said the incident was a poor image for the sport.

"As much as anyone doesn't like refs and they make bad calls, they're there to do a job and you've got to give them some sort of respect for them to do their job effectively.

"I can understand why Thurston was frustrated... they made some questionable calls towards the end, the referees. But the incident he was blowing up about was a right call, Thurston just lost his rag a bit and it all came out.

"Imagine how many young kids saw what Thurston said the other night and have watched countless replays since then.

"This weekend I'd hate to be a junior ref, to see what's going to happen. It's set a precedent and the NRL must be just rolling their eyes that the judiciary panel let him off."

The panel took only 20 minutes to find Thurston not guilty after his lawyer Colin White had argued the incident couldn't be classified as detrimental conduct because the NRL had kept footage of it on its website until late Wednesday afternoon.

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