An American student, who crashed killing three of his classmates and injuring four others, has been convicted and discharged with only a period of disqualification imposed.

Stephen Houseman, 20, pleaded guilty in the Auckland District Court today to three counts of careless driving causing death and four counts of careless driving causing injury.

Austin Brashears, 21, Daniela Rosanna Lekhno, 20, and Roch Jauberty, 21, died when a van driven by Houseman rolled on a bend of State Highway 46, south of Turangi, on May 11.

A police summary of facts said the students were part of a group travelling in three vans on their way to walk the Tongariro Crossing. They were from Boston University and on a six-month exchange programme.

It was the first time Houseman had driven here.

The crash occurred because he let the vehicle move on to the left-hand gravel shoulder of the road and he then over-corrected, swerving to the right, then to the left, causing the van to roll.

Four people who were not wearing seatbelts were thrown from the van with three of them - Brashears, Lekhno and Jauberty - receiving head injuries and dying at the scene. The fourth, Margaret Theriault, received serous injuries and spent a considerable time in intensive care.

Houseman and three others who were wearing seatbelts remained inside and received fractures, bruising and grazes. Houseman had his wrist crushed and required surgery.

Police said Houseman insisted the occupants wear seatbelts before the journey began.

"When asked how the vehicle lost control he stated the van started to shake and he tried to regain control. He could offer no explanation why the vehicle left the road causing him to lose control," the summary said.

Houseman pleaded guilty after Judge Brooke Gibson indicated he would receive a conviction and discharge with only a period of disqualification from driving.

Defence lawyer Marie Dyhrberg then applied for a discharge without conviction, arguing that the consequences of a conviction would outweigh the gravity of the offence.

Houseman was studying hospitality management and a conviction would inhibit him from gaining employment in which he would have to work at hotels outside the United States, Dyhrberg said.

The judge accepted that Houseman had "very good future prospects and has led an exemplary life".

"It was a classic careless driving case where the carelessness was slight but the outcome was massive."

The judge said the consensus of the victims and their families was that they did not want to see Houseman saddled with a criminal conviction.

Houseman was supported in court by a large number of Boston students, their parents, diplomats from the United States consulate and staff from the Langham Hotel, where Houseman worked.

The judge also accepted Houseman had shown true remorse by visiting the victims in hospital and attending the memorials of those who died.

He ruled that a conviction would not outweigh the seriousness of the offending. He was convicted and discharged but disqualified from driving for six months.

- © Fairfax NZ News