A law student who killed a man with a single punch during a night out drinking on the Isle of Wight has been found guilty of manslaughter.
Father-of-10 Gary Stacey, 49, died from brain injuries following an altercation with Ryan Cooper in Newport last year.
Cooper's trial heard it was not in dispute that the karate black belt threw a punch, but the 21-year-old maintained it was in self-defence.
He was given a six-year sentence, with a minimum of three years in custody.
Jurors at Winchester Crown Court heard that Cooper, of Alma Road, Southampton, had been ejected from Yates's pub for being drunk on a night out with friends on Valentine's Day last year.
Earlier in the evening he had posted on Facebook about taking "the biggest line of cocaine" as well as drinking "half a litre of vodka".
CCTV of the moment Cooper punched Mr Stacey in St James Street shortly before 04:00 GMT was shown in court.
The defence maintained he threw a punch in self-defence after a "verbally threatening" Mr Stacey approached him "marching with aggressive nature" and with clenched fists.
The jury had heard a recording of the 999 call in which Cooper phoned the police to hand himself in.
The prosecution said his version of events was "a campaign of cover-ups and lies" after an unprovoked attack.
Mr Stacey suffered a fractured eye socket and bleeding on the brain, after hitting his head on the ground. He died later after being airlifted to Southampton General Hospital.
Passing sentence, Mr Justice Warby said Cooper had not acted "in lawful self-defence" when he struck Mr Stacey with a "powerful punch".
He said the episode was "influenced by the effects of what was clearly excessive alcohol consumption" and said Cooper had run away from the scene knowing he had "done something wrong and indefensible".
He told Cooper: "This is a very sad case. You will miss your finals [university exams]. There will inevitably be an impact on your future career choices.
"I am sure you would take back those two seconds if only you could. But of course you can't. The case is sadder for Gary Stacey and his family."
After the hearing, Mr Stacey's family issued a statement describing him as a "loving father and dedicated family man".
"We were denied the opportunity to celebrate his 50th birthday by the actions of Ryan Cooper and are pleased that this sentence has found justice for Gary," it added.
Det Ch Insp Liz Williams said: "This is sadly yet another reminder that one punch can kill and that alcohol related violence can have devastating consequences."