The U.S. Supreme Court says it will not consider a challenge to the terms of a concussion-related settlement between the National Football League and more than 20,000 retired players.

The deal settled a class-action filed by former players who accused the NFL of covering up what it knew about the link between playing professional football and the degenerative brain disease known as chronic traumatic encephalopathy, or CTE.

The settlement was given final approval by a judge in 2015. But the deal was later challenged by a small group of dissenting players who argued that it "unfairly favored currently injured retirees and left thousands of former players who have not yet been diagnosed with neurological diseases without any recourse," NPR's Nina Totenberg reported.

Attorneys for those players also questioned whether the settlement should be renegotiated in light of comments made by the NFL's executive vice president for health and safety, who acknowledged during congressional testimony earlier this year that there is a connection between football and CTE, as The Two-Way reported.

But a federal appeals court found the admission did not invalidate the deal, under which the NFL did not admit wrongdoing, and the Supreme Court upheld the lower court's decision.

Now, with the final legal challenge over, payouts to individual players can begin.

The settlement will pay medical and other benefits to players who suffered concussions and related injuries and could cost the NFL up to $1 billion over 65 years depending on how much the league ends up paying to each of the more than 20,000 former players covered, as we have reported.

The Associated Press reported that the NFL estimates 6,000 former players, or nearly one-third, "could develop Alzheimer's disease or moderate dementia," and that the average payout would be about $190,000.

Here's our previously reported breakdown of the maximum financial awards related to different brain injuries diagnosed in former players.

  • Level 1.5 neurocognitive impairment: $1.5 million
  • Level 2 neurocognitive impairment: $3 million
  • Parkinson's disease: $3.5 million
  • Alzheimer's disease: $3.5 million
  • Death with CTE: $4 million
  • ALS (Lou Gehrig's disease): $5 million

In an information page about the settlement, "level 1.5 neurocognitive impairment" is described as "early dementia [with] moderate to severe cognitive decline." Level 2 is described as "moderate dementia [with] severe cognitive decline."

One of the lead plaintiffs in the class-action against the NFL was Kevin Turner, who died earlier this year at age 46. Turner played for both the Philadelphia Eagles and the New England Patriots; he was diagnosed with ALS six years before he died.

But that diagnosis was incorrect, according to researchers at Boston University. In November, the Boston Globe reported that "Turner spent his excruciating final years stricken with a severe case of football-related chronic traumatic encephalopathy, or CTE, which caused a motor neuron disease similar to ALS."

CTE can be diagnosed only through a brain autopsy after a person has died.

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