The "concussion discussion" has been going on for a long time in sport, and the talking is far from done.
Step by step, however, a combination of academic findings, rending personal testimony and legal action is creating significant change within sports where physical contact is a constant, or even the whole point.
The long-running debate about whether boxing, where concussion is the gold medal outcome, should be banned, is now being extended to other combat sports such as mixed martial arts.
The International Mixed Martial Arts Federation (IMMAF) was among sporting Federations to have submitted evidence online in March to the United Kingdom Government's Department of Culture, Media and Sport (DCMS) Inquiry into Concussion in Sport, the latest enquiry in this broad area.
Under the chairmanship of Julian Knight, this Select Committee inquiry has been established to examine links between sport and long-term brain injury and will "consider scientific evidence for links between head trauma and dementia and how risks could be mitigated".
The findings are expected to emerge shortly before or after the Government’s summer recess.
The enquiry is not restricted to particular sports, although combat sports, football and both codes of rugby have been high priority - and high profile - considerations.
As the BLM Law website points out, the committee is not considering material involved in ongoing legal proceedings but will "consider potential implications of successful legal action and what impact that could have on sport in the longer term".
The firm sees these two intentions as being mutually exclusive.
Last December England Rugby World Cup winner Steve Thompson and seven other former players initiated a claim amounting to millions of pounds against the game’s authorities for negligence, claiming the sport has left them with permanent brain damage.
Letters were sent by the group to World Rugby, the Rugby Football Union and the Welsh Rugby Union.
Although details of the specifics of the letter have not been released, players including Thompson, former Wales international Alix Popham and former England flanker Michael Lipman have recently spoken out on the topic and have been reported as being part of the claim.
All eight players to have come forward so far have been diagnosed by neurologists at King's College, London, with early onset dementia and probable Chronic Traumatic Encephalopathy (CTE).
CTE can develop when the brain is subjected to numerous small blows or rapid movements - sometimes known as sub-concussions - and is associated with symptoms such as memory loss, depression and progressive dementia.
The disease was discovered by Dr Bennet Omalu in American football player Mike Webster, and the subject of the film Concussion starring Will Smith. In 2011, a group of former American football players started a class action against the National Football League (NFL) and won a settlement worth about $1 billion (£700 million/€805 million).
The first legal move of its kind in world rugby could lead to profound changes in the game. Lawyers for the group have suggested another 80 former players between the ages of 25 and 55 are showing symptoms and have serious concerns.
Thompson, who played in every England match when they won the 2003 World Cup, told BBC Sport: "I can't remember any of those games. It's frightening.
"When we first started going full-time in the mid-1990s, training sessions could quickly turn into full contact.
"There was one session when the scrummaging hadn't gone quite right and they made us do a hundred live scrums. When it comes to it, we were like a bit of meat, really.
"The whole point of us doing this is to look after the young players coming through. I don't want rugby to stop. It's been able to give us so much, but we just want to make it safer."
The rugby authorities have stressed how seriously they treat the subject, with World Rugby President Sir Bill Beaumont, the former England and Lions lock forward and captain, pointing out that he himself had to give up the game on doctors’ advice in 1982 after suffering repeated concussions.
Among the experts assembled by the Select Committee is Professor Willie Stewart, a consultant neuropathologist who acts as adviser to World Rugby on concussion.
"Rugby has made great developments in understanding how you can assess players with brain injury on the field," said Professor Stewart at the opening session. "That should be the model and the benchmark that (other) sports start from."
Rugby union has altered its rules significantly since 2019 to clamp down on reckless tackles involving the head, and the results have been clearly demonstrated in key matches including those in the recently concluded Six Nations tournament.
But there remain areas of uncertainty in interpretation. For example, the red card earned by England’s Manu Tuilagi for a corner-flag tackle on Welsh winger George North during their 2020 Six Nations match was described by The Rugby Paper columnist Nick Cain as a "travesty and an insult to courage".
"It was wrong not because strong officiating and disciplinary action to mitigate against concussion in this sport are mistaken, but because the application of the law in the case of Tuilagi’s 74th minute cover-tackle on George North at Twickenham last weekend was mistaken, and reflects a one-size-fits-all disciplinary mentality that makes unreasonable demands on players," Cain wrote.
He pointed out that, as Tuilagi was lining-up his last-ditch attempt, North suddenly and significantly dropped as a result of a half-tackle from England’s Henry Slade four metres from the line.
"A split-second later when the impact is made North has lost speed and fallen to his knees - which almost certainly makes him about half his original height - and Tuilagi, who has virtually no time to make any adjustments, has his left arm outstretched, but finds nothing to encircle, and has tucked his right arm close to his body," he wrote.
"As Tuilagi's right arm/shoulder makes contact with North he is almost sitting down, and is probably no higher than three feet from the turf. He makes a brief, grazing contact with the side of the wing’s head, but it is crystal clear from the footage that the main force of Tuilagi’s right shoulder is to North’s right shoulder - and it is this that knocks him into touch."
Cain then adds that an earlier head-high "hit" on Tuilagi by Welsh centre Hadleigh Parkes only resulted in a penalty…and so, as the laws change, the familiar narrative of inconsistent refereeing continues.
Sub-concussions cannot be detected on the pitch or in any post-match examination. CTE can only be diagnosed in a brain after death.
It has been found in the brains of dozens of former NFL players, as well as a handful of deceased footballers, including former West Bromwich Albion and England player Jeff Astle. A re-examination of his brain in 2014 found he had died from CTE.
At Astle’s inquest, the coroner recorded his death as an industrial injury, citing repeated minor traumas from heading the leather footballs that were standard issue during his playing days.
Astle’s daughter, Dawn, has spent many years raising the issue of brain damage following her father’s death aged 59 in 2002 and started a Justice for Jeff campaign, calling for an independent inquiry into the possible link between heading footballs and brain damage.
Further impetus was added to her cause in 2019 when a report by the University of Glasgow found former professional players were three-and-a-half times more likely to die of degenerative brain disease.
The ground-breaking University of Glasgow survey involved comparing the deaths of 7,676 ex-players to 23,000 from the general population. The sample was taken from men who played professional football in Scotland between 1900 and 1976.
Stewart reported that "risk ranged from a five-fold increase in Alzheimer's disease, through an approximately four-fold increase in motor neurone disease, to a two-fold increase in Parkinson's disease in former professional footballers compared to population controls".
In February 2020 the Football Associations of England, Scotland and Ireland advised coaches that there should be "no heading in training in the foundation phase" - which covers primary school children, or under-11 teams and below.
There were also new rules for age ranges up until 18, with headers being kept a "low priority" and gradually becoming more frequent in training until the age of 16.
Pointing out that there was no evidence in the Glasgow study that linked incidences of the disease with heading the ball, the FA said the new guidance had been issued to "mitigate against any potential risks".
The guidelines were also adopted by UEFA last June.
In December last year another facet of player welfare was addressed when the International Football Association Board (IFAB) approved "extensive trials" for concussion substitutes.
Competition organisers and Football Associations across the world were encouraged to apply to the IFAB and FIFA to take part in the trials in which permanent substitutions can be made if a player is suffering from "actual or suspected concussion".
Members agreed that if a player sustains a bang to the head they should be "permanently removed" from the match to "protect their welfare", but their team "should not suffer a numerical disadvantage".
The IFAB claimed multiple head injuries could have "very serious consequences" and maintained the new approach to concussion sent "a strong message" and also reduced the pressure on medical personnel to make a quick assessment on the pitch and to be inclined to keep players in action.
"It is simple to operate and can be applied at all levels of the game, including most of football that is played without doctors or medically qualified staff available on site," the statement from IFAB read.
Last month concussion guidelines for Para-football were published in the British Journal of Sports Medicine for the first time.
Para Football, a foundation and worldwide body of football for persons with disabilities, said publication of the new guidelines - called the Para Concussion Position Statement - was a "major milestone" for concussion management of players.
"Concussion is a huge global issue for all forms of football, and has been the subject of extensive scientific and media attention in recent years," Para Football said.
"To date, however, there has been no specific guidance and advice to shape the assessment and management of Para-athletes with concussion."
A further indication of the seriousness with which the game is beginning to treat head trauma emerged this week when FIFA’s medical director, Andrew Massey, announced that "concussion spotters", whose job is to identify from the stands possible brain injuries, are to be introduced at the World Cup finals in Doha next year.
Concussion spotters are already a standard in the NFL and rugby union, but have yet to be adopted across football and their use in Qatar will be a first at a major international tournament.
Massey confirmed all FIFA tournaments would also now have video replays for team doctors to study for signs of concussion among players.
Debate over the dangers inherent in combat sports such as boxing and mixed martial arts continues to take a more polarised form.
Peter McCabe, chief executive of the Headway brain injury charity, told the DCMS Inquiry that he would immediately ban both boxing and cage fighting "as the primary objective of each sport is to injure or knock out the opposing fighter".
The IMMAF has criticised "unsubstantiated references" to mixed martial arts made during the first DCMS hearing on March 3.
The IMMAF and EMMAA’s submission at the end of March reportedly expressed concern about the lack of Government regulation of combat sports in the UK, which they cite as a factor creating great risk to participants.
"There is no law in this country that requires participants and stakeholders of martial arts or combat sports to adhere to any minimum safety standard or to comply with any form of governance," said IMMAF chief executive Densign White.
"And for as long as MMA is not officially recognised as a sport by Sport England, our power to govern or to regulate through local authorities is further undermined.
"It is our view, that it is the responsibility of the Government to ensure that the health and safety of participants in sport is guaranteed, as they are the only agents with the power to do so."
The IMMAF has said it has produced pioneering work with UK-based medical charity Safe MMA, and its in-event medical protocol.
Safe MMA is cited as providing independent medical screening, management of injury suspensions and the provision of medical advice and information to athletes.
The organisation added that it stands alone in combat sports in its banning of head strikes for under-18s, based on the reasonable age of consent.
"We believe that international sports NGOs have too much power in deciding which sports National Sports Authorities should recognise," said IMMAF President Kerrith Brown.
"As has been well documented in the international sports press, IMMAF has been blocked from gaining international sport recognition for, what we believe are commercial reasons, despite meeting all known governance criteria.
"The ultimate impact of these politics at a grassroots level in many countries is that participants of non-recognised sports can find themselves outlawed, as they are discriminated against in accessing basic medical and professional services that should mitigate risk, thus making sports less safe.
"We are keen to work with the British authorities to address this."
The DCMS has also heard evidence from boxing, ice hockey and skeleton during its hearings.
Its conclusions are likely to bring about another series of significant shifts towards greater safety in this area of sport. But that is a long road, and its future direction is still uncertain.