NFL commissioner Roger Goodell has explained the league appealed the advised six-game ban for Deshaun Watson because a disciplinary hearing found "egregious" violations and "predatory behaviour".
Watson faced 24 civil lawsuits following sexual assault and misconduct allegations. He was not charged by two grand juries and has strenuously denied any wrongdoing.
The Cleveland Browns quarterback settled 20 of the lawsuits in June, with a further three settlements reported at the start of August ahead of the verdict of his NFL hearing.
Former US district judge Sue L. Robinson oversaw those proceedings and concluded Watson should miss six games with no additional fine.
But the NFL felt, having reviewed that decision, the evidence uncovered by Robinson required a harsher punishment, and it has used its right to appeal.
It is widely reported the league believes Watson should be suspended for the entire 2022 season, and Goodell outlined why this is the case.
"We've seen the evidence," he said. "[Robinson] was very clear about the evidence, should we enforce the evidence – that there were multiple violations here, and they were egregious, and it was predatory behaviour.
"Those are things that we always felt were important for us to address in a way that's responsible."