Negligence in Contact Sports: The Legal Challenges of Rugby-Related Neurodegenerative Disease Claims
Author: Scott McCulloch, M.S. (Psychology and Neuroscience), LLB Student
Abstract: Traumatic brain injuries (TBI) and their long-term neurological consequences have become a growing concern in contact sports such as rugby, American football, boxing, and soccer. Scientific research has established a clear link between repetitive head trauma and neurodegenerative diseases, including Chronic Traumatic Encephalopathy (CTE), Alzheimer’s, and Parkinson’s disease. Despite this, sports governing bodies have struggled to implement and enforce effective safety measures, leading to legal and ethical debates over their duty of care.
This article provides a comprehensive analysis of both the scientific and legal dimensions of the issue. It examines the biological mechanisms by which repeated head injuries contribute to cognitive decline and explores legal precedents, including the NFL Concussion Settlement, NCAA concussion litigation, and ongoing lawsuits against World Rugby. A central challenge in these cases is the doctrine of Volenti Non-Fit Injuria, which argues that athletes willingly accept the risks associated with their profession. However, legal claims suggest that many players were not adequately informed of the long-term dangers of TBI, raising questions about informed consent and organizational liability.
Beyond legal and scientific concerns, this article highlights the devastating quality-of-life impact for athletes suffering from neurodegenerative diseases. While professional careers last only a few years, the consequences of repeated brain trauma persist for a lifetime. The discussion challenges whether current concussion protocols, safety regulations, and legal frameworks are sufficient, and whether more radical changes are necessary to prevent future generations from experiencing the same fate.
Ultimately, this article argues for a re-evaluation of risk management in contact sports, balancing athlete autonomy, organizational responsibility, and long-term health implications. As scientific evidence continues to mount, the legal system will play a crucial role in determining how far sports organizations must go to protect their players—and whether failure to act constitutes negligence. The future of contact sports hinges on the willingness of stakeholders to acknowledge and address this crisis before it is too late.
1) Introduction
This article presents a combined legal and scientific analysis, examining the factual correlation between participation in contact sports and the subsequent diagnosis of neurodegenerative diseases, where traumatic brain injury (TBI) is suggested as a potential causative factor. It explores the issue from both a tort law and neuroscience perspective, referencing key research on neurodegeneration while establishing legal precedent from relevant negligence cases.
2) Key Issues
Recent studies have identified a concerning correlation between participation in contact sports—including rugby, American football, boxing, and soccer—and an increased risk of developing neurodegenerative diseases, particularly chronic traumatic encephalopathy (CTE) and other forms of dementia. Repetitive head impacts (RHI) from tackling, collisions, and even heading the ball in soccer have been linked to an elevated risk of long-term brain damage.
A landmark international study led by Professor Willie Stewart at the University of Glasgow examined the brains of 31 former amateur and elite rugby union players and found CTE present in approximately 68% of cases (University of Glasgow, 2023). The study also revealed that each additional year of play increased the risk of developing CTE by 14%, regardless of the player's position or level of participation.
Findings from American football support similar conclusions. Research from the DIAGNOSE CTE Research Project demonstrated that former NFL players exposed to repeated concussive and subconcussive impacts showed structural brain abnormalities associated with neurodegenerative disorders (Arciniega et al., 2024). Another Cureus study identified that NFL athletes are at significantly higher risk of developing CTE, highlighting that despite increasing awareness, the sport continues to promote play styles that lead to these injuries (Hasan et al., 2024).
Similarly, boxing has long been associated with brain injuries, including dementia pugilistica—now classified as a variant of CTE. Studies show that boxers with long careers sustain more severe neurodegenerative changes compared to other contact sports (Zeine et al., 2024).
Even soccer, which is often considered a lower-contact sport, presents risks. A 2024 German Journal of Sports Medicine study found that players who frequently head the ball exhibit changes in brain kinematics similar to those seen in early-stage neurodegeneration (Kern et al., 2024). Furthermore, a 2024 BMJ Open study analyzed long-term cognitive decline in former professional soccer players, linking repetitive heading exposure to a heightened risk of developing Alzheimer's disease (Zimmerman et al., 2024).
Individual Cases Highlight the Impact
Prominent athletes have brought personal attention to these risks.
Steve Thompson, a member of England's 2003 Rugby World Cup-winning team, was diagnosed with early-onset dementia and probable CTE at age 42. He has reported significant memory loss, including an inability to recall the World Cup victory or moments with his children.
Carl Hayman, a former All Black, was diagnosed with early-onset dementia and probable CTE in his early 40s, attributing his condition to repeated head traumas sustained during his career.
In American football, Hall of Famer Junior Seau tragically took his own life in 2012, and posthumous analysis revealed he had severe CTE, reinforcing concerns over long-term consequences for NFL players.
These findings underscore the potential long-term neurological risks associated with contact sports, necessitating further research and consideration of enhanced safety measures across multiple disciplines.
3) Understanding Negligence in Sports Injury Claims
To establish a negligence claim in the context of contact sports and traumatic brain injuries (TBI), a claimant (typically a former or current athlete) must prove four key legal elements:
Duty of Care – The sports governing body, team, or organization must have a legal responsibility to take reasonable steps to protect players from foreseeable harm. In contact sports, this includes implementing concussion protocols, ensuring proper medical care, and providing adequate safety education.
Breach of Duty – The claimant must show that the responsible party failed to meet this duty of care. A breach occurs when a governing body does not take reasonable precautions to prevent brain injuries, such as failing to enforce concussion protocols or downplaying the risks of repeated head impacts.
Causation – It must be demonstrated that the breach of duty directly caused the injury. In the case of neurodegenerative diseases like Chronic Traumatic Encephalopathy (CTE), proving causation can be difficult, as it requires linking long-term brain damage to repeated sports-related trauma.
Damage – The claimant must have suffered actual harm, such as cognitive decline, dementia, or other neurological conditions, resulting in financial loss, diminished quality of life, or ongoing medical needs.
In legal cases against sports organizations, disputes often arise over whether the governing body truly breached its duty of care or if the risk of injury was an inherent part of the game (assumed by the player). These debates shape the legal landscape of concussion litigation and continue to influence safety regulations in professional sports.
4) Legal Precedents and Court Rulings on Traumatic Brain Injuries in Contact Sports
In recent years, legal action surrounding traumatic brain injuries (TBI) in contact sports has gained significant momentum. Courts have increasingly addressed claims by former athletes who developed neurodegenerative diseases, arguing that sports organizations failed to adequately protect players or warn them of long-term risks.
One of the most high-profile cases in this area came out of the United States. The NFL Concussion Settlement (2013-2016), in which the National Football League (NFL) agreed to a $1 billion settlement with thousands of former players who developed conditions like CTE, Alzheimer’s, and Parkinson’s (Gove, 2011). The lawsuit alleged that the NFL was aware of the dangers of repetitive head trauma but failed to act, setting a legal precedent for future sports-related brain injury claims.
Similarly, NCAA concussion litigation has become a major issue, with cases such as Arrington v. NCAA (2014) prompting the association to introduce stricter concussion protocols and a $70 million medical monitoring fund for former college athletes (Sabin & Goldsmith, 2022). Important to note, this case highlighted the duty of care owed by governing bodies to ensure adequate safeguards against head injuries.
In rugby, legal actions have begun to emerge as well. Former professional players, including Steve Thompson and Carl Hayman, are currently suing World Rugby, the Rugby Football Union (RFU), and the Welsh Rugby Union (WRU) for negligence (Cordato et al., 2022). They argue that these governing bodies failed to implement proper concussion management policies, leading to their diagnoses of early-onset dementia and probable CTE.
Boxing has also seen legal scrutiny, with cases like Morrison v. USA Boxing (2018) bringing attention to the lack of medical oversight in combat sports (Zirkel, 2016). Courts have recognized that sports federations have a responsibility to mitigate risks associated with repeated head trauma, reinforcing the need for more stringent safety regulations.
Legal Principles in Sports Brain Injury Cases
Negligence & Duty of Care: Courts have increasingly applied tort law principles, holding sports leagues accountable for failing to inform players of the risks of repeated head injuries.
Statutes of Limitations: Many athletes do not realize they have suffered long-term effects of brain trauma until years after retirement, raising legal questions about the applicability of the discovery rule (Goldsmith, 2022).
Workers' Compensation Claims: Some former athletes have sought compensation through workers' compensation laws, arguing that their injuries resulted from occupational hazards rather than voluntary risks (Modery, 2011).
Ongoing Legislative Efforts
In the U.S., states have introduced concussion protection laws for youth and collegiate athletes, requiring mandatory rest periods following head injuries.
In the U.K., parliamentary hearings have examined whether rugby and football governing bodies have done enough to protect players.
Helmet safety regulations have been introduced in professional leagues like the NFL and NHL to minimize the risk of severe concussions.
5) Duty of Care in Contact Sports and Concussion Protocols
Sports organizations have a legal and ethical duty of care to ensure player safety, particularly regarding traumatic brain injuries (TBI) and concussions. This duty extends to preventing, diagnosing, and properly managing head injuries while ensuring that athletes are informed of the risks. Over the years, various sports governing bodies have implemented concussion protocols, though concerns remain about their effectiveness and enforcement.
Legal and Ethical Responsibility of Governing Bodies
The duty of care in sports is based on negligence law principles, where sports organizations may be liable if they fail to take reasonable steps to prevent foreseeable harm. Governing bodies must:
Educate players and coaches about TBI risks.
Implement concussion protocols that require proper medical evaluations.
Enforce safety measures such as mandatory rest periods for injured players.
Provide long-term medical support for retired athletes facing neurodegenerative conditions.
A 2024 study by López Frías & McNamee (Sport, Ethics, and Philosophy) highlights the conceptual, ethical, and legal implications of concussion management in contact sports. The study argues that sports organizations have been slow to fully acknowledge the dangers of repetitive head impacts, leading to lawsuits and public criticism (López Frías & McNamee, 2024).
Examples of Concussion Protocols
Rugby (World Rugby)
Introduced the Head Injury Assessment (HIA) protocol, requiring players with suspected concussions to undergo an immediate medical evaluation before returning to play.
Implemented the "Graduated Return-to-Play" protocol, mandating a minimum stand-down period for players who sustain head injuries.
American Football (NFL)
Established a Concussion Protocol, which mandates that independent neurologists assess injured players before allowing them to return.
Following the Tua Tagovailoa concussion controversy (2022), the NFL strengthened its policy, preventing players from returning to a game if they exhibit ataxia (loss of coordination).
Soccer (FIFA)
Introduced temporary concussion substitutions in 2021, allowing teams to make additional substitutions when a player suffers a head injury.
Despite this, criticism remains regarding the handling of head injuries in high-stakes matches, with some players continuing to play despite visible concussion symptoms.
Boxing (WBC & AIBA)
Instituted mandatory medical suspensions for fighters who suffer knockouts or repeated head trauma.
Some jurisdictions require fighters to undergo brain scans before being cleared to compete.
Ice Hockey (NHL)
Implemented the Concussion Spotter Program, where neutral officials monitor games for signs of head injuries and can remove players from play.
However, lawsuits from former players suggest that historically, the league did not adequately warn athletes of long-term risks.
Lack of Enforcement and Persistent Issues
Despite these measures, enforcement remains inconsistent. A 2024 study found that athletes often underreport concussions due to pressure to continue playing, and coaches sometimes disregard protocols to keep star players in games (López Frías & McNamee, 2024). Legal claims from former professional players, particularly in rugby and American football, argue that these sports bodies failed to provide adequate medical warnings about the long-term dangers of head trauma.
These concerns highlight the need for stronger regulatory oversight, independent medical decision-making, and increased education to ensure that athletes fully understand the risks associated with repetitive brain injuries.
6) The Challenge of Establishing a Breach of Duty: Assumption of Risk in Contact Sports
One of the central legal challenges in holding sports governing bodies liable for traumatic brain injuries (TBI) lies in the doctrine of Volenti Non-Fit Injuria—"to a willing person, injury is not done." This legal principle suggests that athletes who voluntarily participate in high-contact sports accept the inherent risks involved, including the possibility of sustaining concussions and long-term neurological damage. At the professional level, players are generally considered competent adults who knowingly and willingly assume these risks in exchange for the rewards of competition, financial compensation, and personal fulfillment.
In many legal defenses, sports organizations argue that because head injuries are well-documented risks in sports like rugby, American football, and boxing, players consent to these risks by stepping onto the field or into the ring. Furthermore, contracts, waivers, and player agreements often contain clauses acknowledging the dangers associated with repeated impacts, reinforcing the argument that athletes accept these hazards as part of their professional careers.
Another relevant legal doctrine, Res Ipsa Loquitur—"the thing speaks for itself"—is sometimes invoked in cases where the injury sustained is so obviously linked to the activity that no further proof of negligence is needed. However, in TBI cases, governing bodies often counter that while brain injuries are possible, they are not inevitable nor exclusively caused by sports participation. They may argue that multiple variables contribute to neurological decline, including genetics, lifestyle factors, and injuries sustained outside the sport.
However, a gray area emerges when considering the extent to which athletes were fully informed about the long-term consequences of repetitive head trauma. While governing bodies claim that players assume the risk, legal challenges often argue that informed consent was never truly given, especially when organizations downplayed or failed to disclose the long-term neurological risks associated with repeated concussions. Cases such as the NFL Concussion Litigation and lawsuits against World Rugby and the NCAA focus on this very issue, contending that sports leagues had access to medical research on CTE and neurodegeneration but failed to warn players adequately.
This legal tension highlights a fundamental question: while players acknowledge the immediate risks of head injuries, can they be said to have assumed the risk of developing irreversible neurodegenerative diseases decades later, particularly if they were not explicitly warned about these dangers? Courts will continue to grapple with this balance between personal responsibility and organizational accountability, shaping the future of liability in contact sports.
7) The Causal Link Between Traumatic Brain Injuries and Neurodegenerative Disease
Scientific research has overwhelmingly concluded that repetitive head trauma, even in the absence of diagnosed concussions, increases the risk of developing neurodegenerative diseases. Traumatic Brain Injuries (TBI) and Repetitive Head Impacts (RHI) cause progressive damage to brain structures, leading to chronic conditions such as Chronic Traumatic Encephalopathy (CTE), Alzheimer's disease, and Parkinson's disease.
A 2025 hybrid imaging study by Adenekan et al. used advanced PET-MRI scans to analyze the brains of individuals with a history of sports-related head trauma. The results confirmed that even mild but repetitive jolts to the brain result in structural and functional damage, including loss of white matter integrity and accumulation of tau proteins, both hallmarks of neurodegeneration (Adenekan, 2025).
Further research by Blujdea et al. (2025) specifically examined professional boxers and found that elevated levels of glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) proteins—biomarkers of neuronal damage—were significantly associated with long-term cognitive decline and neurodegeneration (Blujdea et al., 2025).
The cumulative nature of minor but frequent brain impacts is particularly alarming. A 2025 University of Akron study found that even low-impact head movements, such as those sustained in soccer heading or repeated football tackles, cause progressive tauopathy (toxic protein buildup in the brain), a key contributor to neurodegenerative diseases (Armstrong, 2025).
Even protective gear such as helmets do not eliminate these risks. Research from Frontiers in Neuroscience (2025) found that helmets may reduce direct skull fractures but do not prevent rotational acceleration of the brain within the skull, a major contributor to shearing injuries, microvascular damage, and neuroinflammation (Kumar & Bhaskar, 2025).
A growing body of literature has linked TBI to early-onset neurodegeneration. A 2025 Journal of Neuroinflammation study highlighted the role of toll-like receptors and inflammasomes in the blood-brain barrier, demonstrating that inflammation caused by head injuries persists for years after initial trauma, contributing to a cycle of neuronal damage and cognitive decline (Acioglu & Elkabes, 2025).
Key Scientific Findings
Repeated head impacts accelerate neurodegeneration, even when concussions are not diagnosed.
Microvascular damage and tau protein accumulation are common in athletes exposed to long-term RHI.
Helmets reduce skull fractures but do not prevent internal brain damage caused by rotational forces.
Neuroinflammation persists long after the initial head injury, exacerbating brain cell death over time.
These findings underscore the urgent need for improved safety protocols, long-term athlete monitoring, and legal accountability in contact sports. The biological evidence linking repetitive brain trauma to irreversible neurological diseases further reinforces the legal and ethical responsibility of sports organizations to mitigate these risks.
8) The Lifelong Impact of Traumatic Brain Injuries and Neurodegenerative Disease on Athletes
For many athletes, the thrill of competition and the glory of professional sports last only a short period, while the impact of traumatic brain injuries (TBI) and neurodegenerative diseases often lingers for decades. The transition from elite athlete to retired player is difficult for most, but for those suffering from CTE, dementia, or Parkinson’s disease, the decline is devastating—impacting memory, cognition, motor skills, emotional regulation, and overall quality of life.
A 2022 study by Dodd et al. found that former athletes with a history of repetitive head trauma report significantly reduced quality of life, experiencing depression, anxiety, mood swings, impulsivity, and an increased risk of suicide (Dodd et al., 2022). Many struggle with financial instability due to cognitive impairments, which limit their ability to work after their sports careers end.
Research from Young et al. (2016) highlights that neurodegenerative diseases linked to TBI cause a progressive loss of independence, requiring long-term caregiving, assisted living, or full-time medical supervision (Young et al., 2016). Former NFL, rugby, and boxing champions who once lived in the spotlight now face isolation, memory loss, and the inability to perform basic tasks, leaving families to carry the emotional and financial burden.
The effects of TBI extend beyond the physical, with studies showing a strong association between head trauma and early-onset dementia, particularly in contact sports. A 2022 systematic review found that athletes who played collision sports for over 10 years have nearly twice the risk of developing neurodegenerative diseases compared to the general population (Piscopo et al., 2022).
The tragedy of these conditions is that they are largely irreversible, and while research is ongoing, no cure exists. Many former athletes have spoken publicly about their experiences, warning younger generations of the long-term consequences of repeated head trauma. Their advocacy has led to improved concussion protocols, but for many, these changes came too late.
This reality raises a critical question: Does the fleeting success of an athletic career justify a lifetime of suffering? While some may argue that athletes willingly take the risk, many did so without fully understanding the long-term implications. As legal, medical, and ethical discussions continue, the focus must remain on protecting current and future generations of athletes from enduring the same fate.
9) Discussion
The interplay between contact sports, traumatic brain injuries (TBI), and neurodegenerative diseases raises critical scientific, legal, and ethical questions. Despite the growing body of research linking repetitive head trauma to long-term cognitive decline, the response from sports organizations, governing bodies, and legal systems remains fragmented and, in some cases, inadequate.
A central issue in this debate is the evolving understanding of risk in contact sports. Historically, athletes, coaches, and leagues operated under the assumption that concussions were short-term injuries, with little acknowledgment of the long-term neurological consequences. Today, research has revealed that even subconcussive impacts—those that do not cause immediate symptoms—can result in progressive neurodegeneration (Dodd et al., 2022). Given this knowledge, the question arises: Are the current safety measures sufficient, or do they merely serve as a legal safeguard rather than a genuine attempt to prevent harm?
From a legal standpoint, the challenge lies in proving breach of duty and causation. While sports organizations owe a duty of care to their players, Volenti Non-Fit Injuria—the legal doctrine of assumed risk—presents a formidable defense. If athletes knowingly engage in high-risk activities, does this absolve governing bodies of responsibility? Alternatively, should sports leagues be required to go beyond basic risk disclosure, ensuring that players fully understand the potential for life-altering brain disease? The numerous lawsuits against the NFL, NCAA, and World Rugby suggest that courts are increasingly willing to hold organizations accountable, yet a uniform legal precedent has yet to be established.
Ethically, the situation demands an examination of the balance between player autonomy and organizational responsibility. Athletes may be willing to take risks in the prime of their careers, but what happens when they can no longer make informed decisions due to cognitive decline? Furthermore, the issue extends beyond professional athletes—youth and amateur players, who are often less informed and less protected, remain vulnerable to similar risks. Should government regulations impose stricter safety measures at all levels of play, or does this infringe upon the essence of competition in contact sports?
Alternative models of play, rule modifications, and technological innovations in protective gear have been proposed, but implementation remains slow. While helmet advancements and concussion protocols have been introduced, they fail to prevent the fundamental biomechanical forces that cause brain injuries. Would stricter enforcement of head-contact limitations in sports like rugby, football, and boxing lead to a safer playing environment, or would it alter the very nature of these sports beyond recognition?
The broader implications extend beyond sports. Military personnel, law enforcement officers, and victims of domestic violence also suffer from TBI-related neurodegeneration. Insights from sports-related brain injuries could enhance medical treatments, early detection methods, and legislative protections for all individuals affected by head trauma. However, these developments depend on continued research funding and policy support.
10) Conclusion
The legal and scientific landscapes surrounding TBIs in contact sports remain at a crossroads. The evidence linking repetitive head trauma to neurodegenerative diseases is overwhelming, yet sports leagues and legal systems struggle to keep pace with these findings. The question is no longer whether contact sports contribute to brain injuries—but rather, what should be done about it?
From a policy perspective, a proactive rather than reactive approach is necessary. The current concussion protocols and safety measures do not eliminate the risk of repeated brain trauma. As research progresses, sports governing bodies must take decisive action, whether through stricter concussion protocols, enhanced medical monitoring, or rule changes designed to minimize repetitive impacts.
Legally, the growing number of lawsuits suggests a paradigm shift in sports liability. Courts will continue to grapple with the tension between athletes’ autonomy and the duty of care owed by organizations. However, waiting for litigation to force change places players at continued risk. Sports organizations must acknowledge their role in shaping the future of player safety before being compelled to do so by judicial intervention.
Ethically, society must ask: Are we comfortable with a system that glorifies sports careers but disregards the long-term suffering of retired athletes? The thrill of competition lasts for a few years, but for those affected by CTE, Parkinson’s, or Alzheimer’s, the consequences last a lifetime.
Ultimately, the goal should not be to eliminate contact sports but rather to ensure that they are played as safely as possible. This requires a combination of research, legal reform, player education, and ethical decision-making at all levels of the sporting world. The future of contact sports depends on how seriously we take this issue today—because the cost of inaction will be measured not in legal settlements, but in the lives and well-being of athletes who have given everything to the game.
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