LOS ANGELES—An attorney for retired National Football League players says their suit against the league and its official helmet manufacturer, which alleges they concealed information about concussions, is as much about raising awareness of brain injuries as winning compensation for the affected players.

The suit, filed last week in California Superior Court in Los Angeles, came as NFL owners and players sought to resolve differences in negotiations over a labor agreement and end a 4-month-old lockout.

Filed on behalf of 75 former NFL players including Mike Duper, Mike Richardson and Vernon Maxwell as well as the wives of some players, the suit alleges that the NFL has known of the potential consequences of concussions since the 1920s, but withheld the information from coaches, players, trainers and the public until June 2010.

In addition to the NFL, the suit also names Riddell Inc., the league's official helmet maker; its affiliates; and its parent, Van Nuys, Calif.-based Easton-Bell Sports Inc.

According to the suit, the players “did not know the long-term nature of concussions and relied on the NFL and (Riddell) to defend them.”

An NFL spokesman said the league “will vigorously contest any claims of this kind.”

Riddell replied to a request for comment with a statement that said, “We have not yet reviewed the complaint, but it is our policy to not comment on pending litigation.”

The suit does not seek a specific damage amount. Instead, an attorney for the players said the plaintiffs will look to establish the extent of injury of each player and seek an award commensurate with the extent of the injury.

“What we characteristically do in these courts is damages awarded according to proof,” said Thomas V. Girardi of the Girardi Keese law firm in Los Angeles who is representing the players. “This is just a more conservative way of doing things.”

He added that the suit is intended as much to raise awareness of concussions in the NFL and effect changes that will reduce brain injuries as it is about getting appropriate compensation for the injured players. “One of the purposes of the case is to see if we can stop other guys getting hurt,” Mr. Girardi said.

Mr. Girardi noted that the effects of the brain injuries to some of the players can be “subtle,” and that the symptoms develop over time. Asked to liken the NFL concussion case to other injury cases, he cited two particular cases he tried.

One was Sandy B. Arnold et al. vs. Ashland Chemical Co., a toxic tort case that's known as the “Erin Brockovich case.” In that case, “You had the chromium (in the drinking water) that the people were subjected to for two decades,” he said. “Cancer doesn't pop up just after you drink the chromium.”

The other was the coordinated action, In Re Vioxx Coordinated Cases, against Merck & Co. Inc. involving the medication Vioxx. “You don't have a heart attack after you pop the first Vioxx pill,” Mr. Girardi said.

The suit against the NFL contends that various player safety rules the league has adopted over the years, such as penalties for grabbing a player's face mask or using a helmet as a weapon to strike an opponent, provide “irrefutable evidence” of the NFL's “duty to protect the health and safety of its players.”

But the suit alleges, among other things, that the NFL “failed to regulate and monitor practices, games, equipment and medical care so as to minimize the long-term risks associated with concussive brain injuries suffered by the NFL players.” It also alleges the NFL failed to require that adequate concussive brain histories be taken of NFL players, ensure accurate diagnosis and recording of players' concussions and warn of the harm associated with repeated concussions.

Sports risk management consultant Herb Appenzeller of Appenzeller & Associates Inc. in Summerfield, N.C., said he thinks the players' chances of winning their suit is hurt by the awareness of those coming into the NFL that they're engaging in an inherently risky profession.

“I'm not real sure that they'd win a lawsuit like this because when they became NFL players, they knew that they were taking a lot of risk,” he said.

Mr. Appenzeller added that he was “surprised” by the suit, given what he sees as a growing awareness of the long-term effects of concussions and steps he thinks the NFL has begun taking to address them.

“We have had a lot of concussions and the recent research has proved that maybe some of the rules we had are outdated,” Mr. Appenzeller said. “I think the new research is getting people conscious not just in football but in soccer, women's sports, anything where there's contact.”

He said he thinks the NFL has been taking steps to address the brain injury issue with moves such as penalties for blows to the head. “Everybody's talking about concussions and what they can do to prevent them,” Mr. Appenzeller said.