In this Jan. 31, 2016, file photo, NHL Commissioner Gary Bettman speaks during a news conference during all-star weekend. (AP Photo/Mark Humphrey)

In a significant blow to the National Hockey League, a federal judge denied the league’s motion to dismiss a class-action lawsuit brought by former players over how the league addressed concussions and related brain trauma.

The NHL had sought to dismiss the retired players’ case on the grounds that its collective bargaining agreement precluded retired players from suing the league. In U.S. District Judge Susan Richard Nelson’s ruling, which was unsealed Wednesday morning, she declared it would be premature to determine which CBAs, if any, would be relevant in the case.

Nelson’s ruling means the NHL will be open to discovery, which could make public reams of private documents. Such a prospect could motivate the NHL to settle the lawsuit first.

Nelson rejected the NHL’s motion to dismiss in strident terms. In her ruling, she wrote the league wanted the case dismissed on the basis of labor law “even though all Plaintiffs in this class action are retired and are no longer subject to any CBA.”

“Discovery is necessary to shed light on the nature of Plaintiffs’ claims, when those claims accrued, and which – if any – CBAs might be relevant,” Nelson wrote. “If a full record ultimately reveals that Plaintiffs’ claims accrued while they were subject to a CBA, and that those claims are substantially dependent on interpretation of the CBA, then the Court could properly determine that the claims are preempted by labor law preemption. In the meantime, however, Defendant’s Motion to Dismiss is premature and must be denied.”

Nelson’s ruling also cited the league’s motion to dismiss hinged on documents from outside the sides’ pleadings, which she wrote constituted a “a cherry-picked record introduced solely to contradict Plaintiffs’ allegations.”

The NHL, according to Nelson’s ruling, already had lost one motion to dismiss on the grounds of federal procedure rules. Wednesday’s ruling regarding labor law set a new precedent and could have ramifications for other sports leagues.

“District Judge Nelson’s order denying the NHL’s motion to dismiss on preemption grounds is an historic decision in American sports [and] labor law,” Stuart Davidson, one of the lawyers representing the players, said in a statement. “We are thankful that retired NHL players will be permitted to continue to pursue their claims that the NHL withheld critical information about the risk of long-term neurological consequences from repetitive head trauma.

“Thousands of retired NHL players continue to suffer from the effects of head injuries suffered on the ice.  The time is now for the NHL to take a leadership role in the international game of hockey and strive to ensure that retired players and their families receive the assistance they need and that the parents of youth hockey players receive truthful information about head trauma.”

No other league has faced the quandary the NHL now finds itself in. In its concussion-related lawsuit in 2013, the National Football League reached a settlement with retired players before Judge Anita Brody could make a ruling on its motion to dismiss. Brody ordered the sides into mediation, a sign to the NFL that she likely wouldn’t dismiss the case. After months of negotiations, the NFL and the retired players reached a $765 million deal. The settlement since has been raised to $1 billion on another judge’s orders.

By reaching a settlement through mediation, the NFL avoided a possible denial of its motion to dismiss. Judge Nelson’s ruling in the NHL case could have an impact on future class-action suits against sports leagues, even if that may be a narrow segment of litigation.

More than 100 former players pledged their names to the class-action suit, which covers all the NHL’s roughly 4,300 former players. They are seeking more comprehensive medical care and claim the NHL has not done enough to promote player safety or assist damaged former players. Their suit rests on the claim that the NHL did not properly warn them of potential risks of head trauma. NHL officials have argued players should have and could have assessed the health risks of professional hockey and knew playing NHL hockey exposed them to brain injury and its effects.