The NFL will ask a U.S. appeals court to uphold a potential $1 billion plan to settle thousands of concussion lawsuits filed by former players.

The appeal is based on complaints that it protects some retirees at the expense of others.

The awards could reach several million dollars for men with Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and advanced dementia. However, they do not cover depression, seizures and mood disorders, which some experts link to concussions.

There are also no awards for future cases of CTE.

"Class counsel bargained away the rights of more than 20,000 former NFL players — many of whom are suffering the serious effects of CTE, fairly called 'football's industrial disease.' This alone is reason to reject the settlement," lawyer Steven F. Molo wrote on behalf of clients appealing the settlement.