By Malcolm Prior
BBC News Online
It is a reckless action that can take somebody's life in a split second.
Drunken street brawls can have fatal consequences
While hundreds of drunken street brawls take place every weekend across the UK, few of the perpetrators - if any - would want a death on their hands.
But one punch is all it takes.
The phenomenon of single-punch deaths has seen scores of people - mainly young to middle-aged men - end up behind bars on manslaughter charges.
Many of them claim to have been caught up in a two-sided brawl they were simply trying to bring to an end.
The reason so many deaths are caused by just one - often average-strength - punch lies not in the blow itself but in the fall suffered by the victim.
Often drunk after a night out, victims simply cannot react quickly enough to protect their heads as they hit the ground.
That can result in what doctors refer to as a primary brain injury, where the impact results in instant damage to the brain tissue, or secondary brain injury, where bleeding in the skull cavity leads to a blood clot pressing on the brain with fatal consequences.
John Black, a consultant in emergency medicine at Oxford's John Radcliffe Hospital, believes the danger of single-punch deaths is "a huge public health issue".
He said: "I think there's a general ignorance about this.
"I think filmmakers have quite a bit of responsibility.
Impact on the floor can result in instant damage to the brain tissue
"You see people get punched repetitively and getting back up again.
"That simply does not happen in the real world."
Mr Black believes that the issue is so serious that a nationwide team of pre-hospital critical care doctors should be set up to back up paramedics called to the scenes of such injuries.
He also wants regional centres of neurological expertise set up for victims to be taken to immediately and greater training for new accident and emergency doctors to recognise fatal symptoms - even if the victim is drunk.
Together with the influence of sanitised depictions of fights on film and television, the influence of alcohol - both on the victim and the attacker - is often blamed for one-punch deaths.
Detective Inspector Robin Hind, of Thames Valley Police, believes they are a rare danger but the risk should be enough for aggressive drinkers to keep off alcohol.
He said: "I have little sympathy with these people - they have got to be responsible for their own actions.
"If they know they are going to be more aggressive when they have had a certain amount of alcohol they should not drink."
Such a hard line is shared by Norman Brennan, director of the Victims of Crime Trust, which represents many families affected by one-punch deaths.
Oliver Cozens: "I'm too scared to punch now"
He said: "No-one has the right, unless they are acting in self defence, to assault another individual.
"What people seem to forget is an individual has got control over whether they use violence."
One of those convicted is 22-year-old Oliver Cozens, who was jailed for nine months in November 2001.
With one punch he managed to kill a fellow reveller following a row in a taxi queue outside a Southampton nightclub.
Mr Cozens, who is currently in jail for an unrelated conviction for grievous bodily harm, told BBC News Online: "My mates still get into fights and they see the other person get up and walk away from it. So they just do not realise the risk.
"I'm too scared to punch someone now. I'd just walk away."
Mrs Pervin hopes her son's case will serve as a warning
Mr Cozens' mother, Karen Pervin, 43, said: "If I was standing there now I would say just walk away but they don't do they?
"Oliver is going to feel the guilt of having killed someone with that stupid strike to the face for the rest of his life."
Mr Cozens' case has at least served as a warning to his younger brother, Lewis, 17, who has started going out at the weekends.
He said: "I know what can happen, what happened to my brother, people do not realise that."