My friend, whom I played football with in college is irate at the former NFL players who are suing the NFL. He believes they should be grateful for what the NFL did for them rather than pursing legal action. However, many others are angry at the NFL for allegedly covering up the dangers and seriousness of concussions. Some believe the NFL should be financially liable. Regardless of where you stand, the legal process is in the works. If they are deemed liable in civil court, it surely be a gigantic monetary judgment. The NFL does have some legal arguments to be litigated though, before any judgments are handed out.
First, they will argue that they simply were not negligent. Just because there may be damage, does not mean someone else has to pay. Generally, you have to prove they were negligent. The NFL will attempt to show that they made keeping their players safe a priority and that they weren't even aware of the true damages of head injuries.
Second, they will argue that the agreed upon collective bargaining agreements should govern. This is the argument which was successfully used last year, preventing players from obtaining court orders to end the lockout. This same preemption defense was also successfully utilized when the Minnesota Supreme Court refused to allow a wrongful death suit 11 years ago. However, this case may be distinguished by the lawyers because it could be deemed unconscionable. Furthermore, you can't contract out intentional torts if indeed the NFL purposefully hid the dangers. It may be a stretch, but if it cold be guised as an intentional tort, that would negate even the first defense.
Third, the NFL will argue that the players assumed the risk of injury when they entered the NFL. Alas, everyone knows and realizes that football is a dangerous game. Nobody knows this better than the players themselves! Assumption of risk is an often used valid defense in personal injury lawsuits.
Fourth, they will argue contributory negligence. This is sometimes referred to as comparative negligence. The NFL will defend by stating that the players negligence either prevents them from now looking to the NFL for compensation, or that it at least reduces the compensation amounts. The reality is, players often would hide their injuries so they would be cleared to play. Therefore, the league will argue that this negligence is what caused the injuries.
Fifth, the NFL may argue that they were not the cause of the injuries, but rather prior football experience leading up to the NFL for each player. Additionally, other non-football related injuries could have cause the injuries.
The plaintiffs' attorneys will have arguable responses to all of these defenses, and it will be an interesting legal case to follow.