More than 3,000 NFL retirees signed up in the first three days of registration for a $1 billion concussion settlement fashioned to end one of the most protracted and publicly debated fights in the history of the football league, lawyers for both sides said Wednesday.

The news came at an unusual hearing for the typically broadcast-averse federal court system. Speaking from a stage at the National Constitution Center and addressing hundreds of players watching on live stream, U.S. District Judge Anita Brody, the federal judge overseeing the deal, urged former players to register before the Aug. 7 deadline.

Attorneys said they hoped to receive the widest possible audience among the more than 20,000 former players who could benefit from the deal, whether in the form of a financial payout for a specific neurological diagnosis or baseline medical testing for those who currently appear healthy.

The first settlement checks could be issued by early this summer, they said.

"One year from now, I expect to have a lot of money transferred from the NFL to, unfortunately, a lot of sick former NFL players," said Christopher Seeger, co-lead counsel of the team representing the league's retirees.

The settlement, approved by Brody in 2015, resolved thousands of lawsuits that accused the league of hiding what it knew about the long-term health effects of repeated concussions. No cap was placed on the amount the league may have to pay over the next 65 years, but auditors estimate it could reach $1 billion or more.

This week, the NFL is expected to move the first $65 million for injury payments into a trust fund with an additional $120 million to follow within six months.

"The NFL is proud of this settlement," league lawyer Brad Karp said.

Critics of the settlement have questioned whether it offers enough aid to those suffering from less serious conditions such as mood disorders and depression or the most severe impairments like chronic traumatic encephalopathy (CTE), one of the signature conditions tied to athlete's concussions.

But the U.S. Supreme Court declined in December to hear their appeal, allowing the start of the registration period Monday.

Under the settlement's terms, retired players would be compensated on a sliding scale based on age, the number of seasons played, and whether post-career injuries might have contributed to their diagnoses.

Maximum awards of $5 million will go to the sickest players and their families. NFL auditors estimate that more than 6,000 retirees could be eligible to collect an average payment of $190,000 for conditions such as dementia and Alzheimer's disease.

Notably, the settlement does not require the NFL to address allegations that have dogged it for years that top executives knew the risks of long-term complications and repeated concussions and hid them from players.

In exchange, retirees who accepted the deal will not have to prove in court that their mental impairments are directly tied to injuries sustained while playing professional football.

Fewer than 160 potentially eligible former players have formally opted out of the settlement agreement and chosen to take their chances alone in court.