Three men will not face trial for manslaughter over the death of a City trader on Mount Everest, a judge ruled.
Mr Matthews went on the expedition with his friend Jamie Everett
In 1999 Michael Matthews, 22, was the youngest Briton to reach the summit but disappeared on the descent.
A private prosecution brought by his father against three men working for the tour company alleged their negligence contributed to his death.
But Judge Jeffrey Rivlin QC dismissed the case, saying there was no evidence anyone had acted with gross negligence.
Lawyers for the three men, Jonathan Tinker, 47, from York, Henry Todd, 61, from Edinburgh, and Michael Smith, 44, who lives in Switzerland, had applied to Southwark Crown Court to have the case thrown out.
Mr Matthews, who lived in Fulham, south-west London, was an experienced climber who had paid £21,000 to reach Everest's summit with the company, Out There Trekking Ltd.
His group reached the summit on 13 May but on the descent he lost contact with his guide, Michael Smith, who went to free some climbing ropes which had become stuck in snow.
It is assumed he fell to his death as his body has never been found.
His millionnaire father David paid for a private prosecution claiming his son's oxygen supply was faulty, there had been insufficient safety briefings and that Mr Smith failed to keep Michael in his sights.
But the judge said Mr Smith risked his own life to stay at the scene and that there was insufficient evidence for a jury to convict anyone of manslaughter by gross negligence.
Dismissing the case, the judge said it was a terrible accident, but the law should not inhibit adventure.
"If ever a criminal charge should be emphatically dismissed this is it," he said.
He added: "A prosecution case was based upon pure and wholly impermissible speculation."
He said it was clear strong emotions were behind the decision to bring the case to trial.
Outside court Mr Matthews said: "The family has never rushed these matters.
"It is one of the reasons that six years have passed. The family has never wished to act vindictively against the defendants."
He added: "We believe that my son's life was given away."
The family had wanted to draw attention to "avoidable dangers" on Everest and in guided climbing, Mr Matthews said.
Mr Tinker said he was glad the case had ended, but expressed his sympathy over the death.
Barrister Patrick Gibbs, representing Mr Smith, said his client had reacted with no "triumphalism" to the judge's decision.
"He would like to embrace Mr Matthews outside and say whatever remains to be said between them about the tragic death which affected them both so nearly."
A manslaughter charge against the three men and Alpine Mountaineering Ltd, formerly Out There Trekking Ltd, was quashed.