Some former professional hockey players are suing the National Hockey League.
In this case, it means they are asking the NHL to pay them money.
Two hundred former players say the NHL didn’t do enough to protect them from concussions.
They say they have brain injuries because hockey is so rough, and they want the NHL to pay for their medical treatment.
The players say they should have been told how dangerous repeated brain injuries are.
They say the NHL waited until 1997 to put a “concussion program” in place, but the league should have known long before that how dangerous concussions are.
The players say the league should have changed the rules of hockey to make it less likely that players would get concussions.