Three clubs have been fined a total of $350,000 for breaching the National Rugby League's concussion protocol, the league announced Monday.
Gold Coast Titans ($150,000), Newcastle Knights ($100,000) and St George Illawarra Dragons ($100,000) were all severely penalised for "failing to follow concussion rules" during round three.
"These are, by far, the heaviest fines ever proposed by the game for concussion breaches," NRL CEO Todd Greenberg said in a statement.
"That is how seriously we take it.
"The clubs involved have the opportunity to respond to the Breach Notices, and we will consider those responses, but our message is clear: we are not going to allow player safety to be put at risk through breaches of the concussion rules."
The league's heavy sanctions come as professional sports associations around the world are taking greater care in treating players with concussion.
Scientific studies have shown that repeated head trauma from playing contact sport is linked to Chronic Traumatic Encephalopathy (CTE), a degenerative brain disease. The consequences are serious, hence the increased vigilance of sport bodies like the NRL.
Former NFL star Junior Seau was found to have CTE at the time he took his own life in 2012. The suicides of other high profile former American footballers, linked to CTE, was chronicled in the 2015 film Concussion.
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