Mr Justice Dyson said that Scottish-based David Cuthbertson, 49, had ignored "elementary and fundamental" practice by failing to fix two ice screws and intermediate single ice screw belays to protect Gerald Hedley, an art conservation expert, who fell to his death on the Tour Ronde, near Chamonix in the Mont Blanc range, in July 1990.
Mr Hedley's son, six-year-old Daniel Woodroofe Hedley, who was not born until after the accident and who sued through his mother, Lynda Woodroofe, of Kilburn in north-west London, will receive damages of up to pounds 200,000 from Mr Cuthbertson's insurers to compensate him for the loss of his father.
Mr Cuthbertson had told the High Court that he was anxious to cross the ice to reach the safety of a rock overhang to avoid the risk of being crushed in a rock fall caused by the hot sun melting ice on the summit.
The judge said the two climbers had been driving in two screws at every "stance" where the climbers met and running belays when one went ahead. Mr Cuthbertson took over as leader when he became concerned about the heat of the sun. When creating a stance on the ice he was unable to fix a second screw because it was blocked with ice.
He then waited 10 to 15 minutes for Mr Hedley to reach him and did not ask him for his own screws which would have been serviceable. "He made a deliberate decision not to waste time by inserting a second screw because he was concerned that they should both move as quickly as possible out of the line of a potential rock fall."
Andy MacNae, national officer of the British Mountaineering Council, said: "I am astounded that anyone should say that the use of two screws and single screw belays is `elementary and fundamental' practice, particularly in the Alps. Speed is your prime concern in the Alps.
"In a guiding situation you make a judgement. You have to be free to use whatever is appropriate."
Roger Payne, the council's general secretary, said: "Safety in alpine climbing is always a balance between security measures and speed ... the strength of safety equipment such as ice screws is limited by the quality of snow and ice at the time, which can be variable to the point of offering no security at all.
"It would be wrong to think that by using a particular belay method that the safety of a party on an alpine ice face can be guaranteed."
Adge Last, the council's training officer, said: "In any mountaineering accident it is normally possible to trace back to a point and say if only those involved had done this or that the accident might have been avoided. But it is wrong to think that because an accident has occurred someone is at fault."