NHL Commissioner Gary Bettman in Las Vegas on May 28. (Ross D. Franklin/Associated Press)

Ken Dryden, a former goaltender for the Montreal Canadiens and member of the Hockey Hall of Fame, was a member of Canada’s Parliament between 2004 and 2011. His books include “Game Change: The Life and Death of Steve Montador, and the Future of Hockey.”

Extensive portions of video depositions related to a concussion lawsuit brought against the National Hockey League by about 150 former players became public this month. The videos include sworn testimony from Commissioner Gary Bettman, Boston Bruins owner and chairman of the league’s Board of Governors Jeremy Jacobs, other team owners, senior league executives and doctors.

The video depositions make for infuriating viewing.

“You’ve seen all the research and the data,” Bettman said, responding to an opposing lawyer during his July 2015 examination, which lasted several hours. “There’s no medical or scientific certainty that concussions lead to CTE.” Chronic traumatic encephalopathy, or CTE, is a degenerative brain disease that has been found in athletes including professional hockey and football players, as well as soldiers and others who have suffered repeated brain injuries. Symptoms of CTE include cognitive impairment, depression, emotional instability and suicidal thoughts.

Bettman was consistent in answering the many questions in his deposition: Because there is no medical or scientific certainty, he said, there is no reason to warn NHL players about the risks of CTE. Nor is there reason, even after the premature deaths in recent years of several NHL “enforcers” such as Bob Probert , Wade Belak , Rick Rypien and Derek Boogaard , to look for a link between fighting in hockey and brain injuries. “I think the sample has been too small,” Bettman said when asked about the players who died. “I would respectfully suggest that, as tragic and as unfortunate as it is, there isn’t even enough circumstantial evidence to draw any conclusions.” Asked whether he had ever spoken to family members of these players about symptoms they had exhibited before their deaths, he replied: “I don’t believe so.” Again, no causal link, no certainty, no reason — why would he?

Phil Anschutz, owner of the Los Angeles Kings, said he was not aware of the term “chronic traumatic encephalopathy.” Asked whether he thought Alzheimer’s disease and dementia are serious medical conditions, he said: “They appear to be.” During Jacobs’s deposition, when he was asked whether he had “ever heard of the neurodegenerative disease known as CTE,” the Bruins’ owner’s answer was succinct: “No.” Asked whether he was aware CTE had been found in the brains of former professional hockey players, Jacobs replied: “I don’t think so. I don’t know.”

Bettman, Anschutz and Jacobs are smart people, and everybody who sees them in these depositions knows they are smart. But almost anyone who sees the videos has heard of CTE and has heard of athletes damaged by concussions. Hockey fans have seen players go down hard, never to play the same way again. They have seen the obituaries for players only a few years after they retired. Hockey fans know something is going on. Then they hear these parsed, pinched words.

The former players’ case has proceeded at a crawl through U.S. District Court in Minneapolis for more than four years. Regardless of the suit’s fate, it has already performed an important service. A deposition isn’t a breezy exchange among friends on “Hockey Night in Canada.” During a deposition, a clever dodge is heard as a clever dodge, and it makes an observer wonder: Why the cleverness? Why the dodge?

Team owners who say they haven’t heard about CTE — how does that make their players and the players’ families feel? The players need to believe the league is doing its absolute best. How about team doctors who already deal with the skepticism or jealousy of colleagues wondering whether they’ve sold out their reputations for a little celebrity? What do they think now?

Or the referees, whose job, in part, is to protect the players. Do they feel betrayed when they read the words of one longtime NHL executive in an email revealed by the lawsuit: “We need to make sure every elbow to the head is not a major penalty. Five-minute majors attract attention. Two-minute minors go away quickly, especially with the media”?

Or even the team owners themselves. They fight a lawsuit to avoid a payout to players that they don’t think is merited. They use arguments that made sense for so long inside the NHL’s community of experts but suddenly in the public light of day are just embarrassing. Losing face is something team owners dislike even more than losing money, especially in front of their families, friends, neighbors and members of the same clubs.

For Bettman and the league’s owners, this isn’t going to get any easier.

These video depositions are revelatory, but they will look tame compared with what is likely to air if the case goes to trial. In the meantime, just as Congress held its first hearing about brain injuries and professional football in 2009, lawmakers in the United States and Canada must surely be readying themselves to start asking questions about the slippery sport of hockey.